Converge round-trips: dedup-key identity, drawer classification, no imposed colors

- Identity: applied entries carry bookhoard_dedup_key (served by the
  server) and echo it back in pushes, so a pull→push cycle updates the
  original server row instead of minting a duplicate (device locators
  never matched web locators under the computed key — every round-trip
  duplicated every annotation). Matching in applyServerAnnotations is
  key-first; a keyed entry that is absent is genuinely new, so pos0
  fallback applies to legacy keyless entries only — a different
  annotation that merely shares a position can no longer be updated
  or, for tombstones, cross-deleted (demonstrated: a deleted
  duplicate's tombstone used to pos0-match a live highlight sharing
  the spot and remove it). Tombstone matching is likewise key-only
  for keyed entries; legacy pos0 fallback is restricted to the same
  annotation kind.
- Classification (v2): the drawer field is the only reliable
  highlight discriminator — KOReader auto-fills text="in Chapter X"
  on page bookmarks, so text-presence turned every echoed bookmark
  into a junk highlight on the web. Bookmarks now take their label
  from note.
- Colors: no color is imposed on applied entries; devices render
  their own default. The web color only changes when the user edits
  the highlight on the device (the edit sets a device color name,
  which the server maps and stores).

main.lua

@@ -879,8 +879,18 @@ function Bookhoard:collectAnnotations()
     for _, bm in ipairs(entries) do
         local sel_text, user_note
         if model == "v2" then
+            if bm.drawer then
                 sel_text = bm.text or ""  -- highlighted text
-            user_note = bm.note or ""   -- user note / bookmark label
+                user_note = bm.note or "" -- user note
+            else
+                -- Page bookmark. `drawer` is the only reliable highlight
+                -- discriminator: KOReader auto-fills text = "in Chapter X"
+                -- on bookmarks (updateItemByXPointer), so text-presence
+                -- would misclassify every bookmark as a highlight on echo.
+                -- The user label lives in `note`.
+                sel_text = ""
+                user_note = bm.note or ""
+            end
         else
             sel_text = bm.notes or ""   -- v1: notes held the highlighted text
             user_note = bm.text or ""   -- v1: text held the note/label
@@ -910,6 +920,13 @@ function Bookhoard:collectAnnotations()
         if percentage then
             entry.percentage = Math.roundPercent(percentage)
         end
+        if bm.bookhoard_dedup_key then
+            -- Echo identity for entries received from the server: lets the
+            -- server match this push to the original row instead of
+            -- minting a duplicate (device locators ≠ web locators, so the
+            -- computed key would never match).
+            entry.dedup_key = bm.bookhoard_dedup_key
+        end
 
         local has_text = sel_text ~= ""
         local has_notes = user_note ~= ""
@@ -1202,7 +1219,22 @@ function Bookhoard:applyServerAnnotations(annotations)
     local changed = false
     local has_pages = self.ui.document.info.has_pages
 
-    local function findLocalByPos0(pos0)
+    local function findLocal(server_entry)
+        -- Identity match by dedup key: survives pos0 drift (improved
+        -- server conversion) and, crucially, never cross-matches a
+        -- DIFFERENT annotation that merely shares the position.
+        local key = server_entry.dedup_key
+        if key and key ~= "" then
+            for i, bm in ipairs(entries) do
+                if bm.bookhoard_dedup_key == key then
+                    return i
+                end
+            end
+            return nil -- keyed but not present: a real new entry
+        end
+        -- Legacy serve (no key): fall back to pos0 matching.
+        local pos0 = server_entry.pos0 or ""
+        if pos0 == "" then return nil end
         for i, bm in ipairs(entries) do
             local p = bm.pos0
             if type(p) == "table" then p = tostring(p.page or "") end
@@ -1267,7 +1299,7 @@ function Bookhoard:applyServerAnnotations(annotations)
         if not isValidPos0(pos0) then return end
         local srv_text = server_entry.text or ""
         local srv_notes = server_entry.notes or ""
-        local idx = findLocalByPos0(pos0)
+        local idx = findLocal(server_entry)
         if idx then
             local bm = entries[idx]
             local cur_text, cur_note = getFields(bm)
@@ -1286,18 +1318,17 @@ function Bookhoard:applyServerAnnotations(annotations)
                 pos1 = makeLocalPos(server_entry.pos1 ~= "" and server_entry.pos1 or pos0),
                 page = makePageFromPos(pos0),
             }
+            if server_entry.dedup_key and server_entry.dedup_key ~= "" then
+                entry.bookhoard_dedup_key = server_entry.dedup_key
+            end
             if has_text then
                 entry.drawer = "lighten"
                 entry.text = srv_text
                 if srv_notes ~= "" then entry.note = srv_notes end
-                -- KOReader renders highlight colors from a fixed name set
+                -- No color imposed: devices render their own default and
-                -- (Blitbuffer.HIGHLIGHT_COLORS); anything else (e.g. a web
+                -- cannot round-trip web colors; the web color only changes
-                -- hex value slipping through) draws nothing useful, so only
+                -- when the highlight is edited here (the edit sets a device
-                -- keep plain names and let the device default apply.
+                -- color, which syncs back by name).
-                local srv_color = server_entry.color or ""
-                if srv_color ~= "" and not srv_color:find("^#") then
-                    entry.color = srv_color
-                end
             else
                 if srv_text ~= "" then entry.note = srv_text end -- bookmark label
             end
@@ -1312,7 +1343,9 @@ function Bookhoard:applyServerAnnotations(annotations)
                 notes = srv_text,
                 text = srv_notes,
             }
-            if server_entry.color and server_entry.color ~= "" then entry.color = server_entry.color end
+            if server_entry.dedup_key and server_entry.dedup_key ~= "" then
+                entry.bookhoard_dedup_key = server_entry.dedup_key
+            end
             if server_entry.chapter and server_entry.chapter ~= "" then entry.chapter = server_entry.chapter end
             table.insert(entries, entry)
             changed = true
@@ -1337,11 +1370,34 @@ function Bookhoard:applyServerAnnotations(annotations)
         end
     end
 
+    local function findLocalByTombstone(del, want_highlight)
+        local key = del.dedup_key
+        if key and key ~= "" then
+            for i, bm in ipairs(entries) do
+                if bm.bookhoard_dedup_key == key then
+                    return i
+                end
+            end
+            return nil -- keyed tombstone: only its own entry may be removed
+        end
+        -- Legacy tombstone (no key): pos0 match, restricted to the same
+        -- annotation kind so a highlight tombstone never eats a bookmark
+        -- that shares the position.
+        local pos0 = del.pos0 or ""
+        if pos0 == "" then return nil end
+        for i, bm in ipairs(entries) do
+            local p = bm.pos0
+            if type(p) == "table" then p = tostring(p.page or "") end
+            if p == pos0 and (not not bm.drawer) == want_highlight then
+                return i
+            end
+        end
+        return nil
+    end
+
     if annotations.deleted_highlights then
         for _, del in ipairs(annotations.deleted_highlights) do
-            local pos0 = del.pos0 or ""
+            local idx = findLocalByTombstone(del, true)
-            if pos0 ~= "" then
-                local idx = findLocalByPos0(pos0)
             local bm = idx and entries[idx]
             local cur_text = bm and (getFields(bm)) or ""
             if idx and cur_text ~= "" then
@@ -1350,20 +1406,16 @@ function Bookhoard:applyServerAnnotations(annotations)
             end
         end
     end
-    end
 
     if annotations.deleted_bookmarks then
         for _, del in ipairs(annotations.deleted_bookmarks) do
-            local pos0 = del.pos0 or ""
+            local idx = findLocalByTombstone(del, false)
-            if pos0 ~= "" then
-                local idx = findLocalByPos0(pos0)
             if idx then
                 table.remove(entries, idx)
                 changed = true
             end
         end
     end
-    end
 
     if changed then
         -- addItem() inserts v2 entries at their sorted position already;