Paint pulled highlights: named colors only + repaint after apply

Two rendering gaps once annotations actually synced:

- KOReader draws highlight colors from a fixed name set
  (Blitbuffer.HIGHLIGHT_COLORS); a web hex value (#ffd54f) resolves
  to nothing useful. The server now serves mapped names, but keep a
  belt-and-braces guard: only accept plain-name colors, let anything
  else (hex or unknown) fall back to the device default.
- applyServerAnnotations mutated the annotation model but never
  requested a repaint — ReaderView paints annotations from the model
  on each redraw, so applied highlights stayed invisible until an
  unrelated refresh. Mark the reader dialog dirty when anything
  changed (same call the native highlight flows make).

main.lua

@@ -1290,7 +1290,14 @@ function Bookhoard:applyServerAnnotations(annotations)
                 entry.drawer = "lighten"
                 entry.text = srv_text
                 if srv_notes ~= "" then entry.note = srv_notes end
-                if server_entry.color and server_entry.color ~= "" then entry.color = server_entry.color end
+                -- KOReader renders highlight colors from a fixed name set
+                -- (Blitbuffer.HIGHLIGHT_COLORS); anything else (e.g. a web
+                -- hex value slipping through) draws nothing useful, so only
+                -- keep plain names and let the device default apply.
+                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
@@ -1367,6 +1374,11 @@ function Bookhoard:applyServerAnnotations(annotations)
         if self.ui.saveSettings then
             self.ui:saveSettings()
         end
+        -- ReaderView paints annotations from the model on each repaint;
+        -- request one so applied highlights appear immediately.
+        if self.ui.dialog then
+            UIManager:setDirty(self.ui.dialog, "ui")
+        end
         logger.dbg("Bookhoard: annotations updated from server")
     end
 end