Fix crash on pull: AnnotationsModified payload must be a table

Event:new("AnnotationsModified", nil) delivered a nil payload to
every handler; ReaderThumbnail:resetCachedPagesForBookmarks does
#annotations on it and crashed KOReader the moment a pull applied
annotations (native KOReader always dispatches this event with a
table payload).

applyServerAnnotations now collects per-changed-item payloads and
dispatches them after applying, mirroring the native add/update/
remove dispatch shapes exactly: {entry, index_modified=index} for
adds (index from annotation:addItem), {bm} for content updates, and
{removed, index_modified=-index} for tombstone removals. This keeps
ReaderView's page-level highlight-box cache invalidation AND its
cached box-index shifting consistent, so mid-session pulls both
paint immediately and keep tap-to-edit associations correct.

Harness-verified: every dispatched payload is a table (explicit
crash-regression assertion simulating ReaderThumbnail's handler),
per-item index_modified values are correct, and all prior behaviors
(color flow, echo suppression, dedup round-trip) still hold.

main.lua

@@ -1232,6 +1232,10 @@ function Bookhoard:applyServerAnnotations(annotations)
     if not model then return end
 
     local changed = false
+    local notify_events = {}
+    local function notify(ev)
+        notify_events[#notify_events + 1] = ev
+    end
     local has_pages = self.ui.document.info.has_pages
 
     local function findLocal(server_entry)
@@ -1321,6 +1325,7 @@ function Bookhoard:applyServerAnnotations(annotations)
             if cur_text ~= srv_text or cur_note ~= srv_notes then
                 setFields(bm, srv_text, srv_notes)
                 if server_entry.color and server_entry.color ~= "" then bm.color = server_entry.color end
+                notify({ bm })
                 changed = true
             end
         elseif model == "v2" then
@@ -1359,7 +1364,8 @@ function Bookhoard:applyServerAnnotations(annotations)
             else
                 if srv_text ~= "" then entry.note = srv_text end -- bookmark label
             end
-            self.ui.annotation:addItem(entry)
+            local index = self.ui.annotation:addItem(entry)
+            notify({ entry, index_modified = index })
             changed = true
         else
             local entry = {
@@ -1435,6 +1441,7 @@ function Bookhoard:applyServerAnnotations(annotations)
             local cur_text = bm and (getFields(bm)) or ""
             if idx and cur_text ~= "" then
                 table.remove(entries, idx)
+                notify({ bm, index_modified = -idx })
                 changed = true
             end
         end
@@ -1444,7 +1451,9 @@ function Bookhoard:applyServerAnnotations(annotations)
         for _, del in ipairs(annotations.deleted_bookmarks) do
             local idx = findLocalByTombstone(del, false)
             if idx then
+                local removed = entries[idx]
                 table.remove(entries, idx)
+                notify({ removed, index_modified = -idx })
                 changed = true
             end
         end
@@ -1462,9 +1471,14 @@ function Bookhoard:applyServerAnnotations(annotations)
         -- ReaderView caches each rendered page's highlight boxes and only
         -- invalidates them on AnnotationsModified — without this, applied
         -- annotations don't paint until restart despite the repaint.
-        -- A non-table payload clears the whole cache (per-item payloads
-        -- only remove the pages of the listed items).
-        self.ui:handleEvent(Event:new("AnnotationsModified", nil))
+        -- Payloads MUST be tables: ReaderThumbnail iterates them, and a
+        -- nil payload crashed KOReader (#nil) on pull. Per-item payloads
+        -- with index_modified mirror the native add/update/remove
+        -- dispatches exactly (page-level cache invalidation + cached box
+        -- index shifting).
+        for _, ev in ipairs(notify_events) do
+            self.ui:handleEvent(Event:new("AnnotationsModified", ev))
+        end
         if self.ui.dialog then
             UIManager:setDirty(self.ui.dialog, "ui")
         end