docs(highlights,notes,opds,progress,analytics): Beam batch 9 — 13 endpoints

Highlights + notes CRUD (media-item scoped, jwt), progress delete,
reading-stats analytics, and the OPDS trio frontmatter'd. OPDS docs are
the first XML entries: example-response intentionally omitted (Atom
responses), gate contract honored via nil-Response registry pins.

Gate fix: group .Use() middleware now parsed (opds.Use(DeviceAuth...
Authenticate) previously resolved to auth 'none'). Registry: 13 entries.
Drift fixed by gate: reading-stats key names (total_reading_time_minutes,
most_active_day_of_week, daily_reading_minutes — draft invented
reading_time_hours/books_completed); notes/highlights list endpoints
return BARE arrays (no {notes:[]}/{highlights:[]} wrapper); create-note
request has no percentage_location/epubcfi_location. New
/tmp/merge_arrays.py handles array-example merges.

make test 9/9.

docs/developer/api/opds/acquisition.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /opds/devices/:deviceId/download/:bookId
+auth: device-token
+area: opds
+---
+<!-- source: internal/handlers/opds.go:795 OPDSHandler.DownloadBook -->
+
 # OPDS Acquisition
 
 Download books and list available formats.

docs/developer/api/opds/feeds.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /opds/devices/:deviceId/catalog
+auth: device-token
+area: opds
+---
+<!-- source: internal/handlers/opds.go:187 OPDSHandler.GetDeviceCatalog -->
+
 # OPDS Feeds
 
 Bookhoard provides OPDS 1.2 feeds for device compatibility.

docs/developer/api/opds/publication.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /opds/devices/:deviceId/cover/:bookId
+auth: device-token
+area: opds
+---
+<!-- source: internal/handlers/opds.go:957 OPDSHandler.GetCoverImage -->
+
 # OPDS Publication
 
 OPDS navigation and publication feeds.