docs(stats): Claude-side pinning — all 4 stats endpoints + UNVERIFIED sweep to zero

Stats docs written handler/service-first (summary/this-week/book-stats
new; library-usage frontmatter'd — its body was already accurate).
Registry: 4 entries on services.UserSummaryStats/WeekSummaryStats/
LibraryUsageStats/BookStats. Family-lens note: library-usage 403s an
explicit library_id outside the visible set (431fec0 rule).

UNVERIFIED sweep (7 -> 0), each resolved against the handler:
- device-usage takes NO date params; popular-books takes only ?limit
  (the 'standard analytics date-range params' claim was wrong)
- link_book media_item_id: no validate tag but service-always-written
- push_stats book-ref field set documented (uuid/sha256/title/authors)
- filter_count: confirmed ParseMediaSearchParams machinery + 400 on bad
  filter + 403 visibility
- facets values element shape pinned: {value, display?, count}
- get_config: dynamic key set IS the contract (reworded, no marker)

make test 9/9.

docs/developer/api/stats/get_summary.md

@@ -0,0 +1,106 @@
+---
+method: GET
+path: /api/stats/summary
+auth: jwt
+area: stats
+---
+<!-- source: internal/handlers/stats.go:33 StatsHandler.Summary -> services/statistics_service.go:213 UserSummaryStats -->
+
+# Get Reading Summary
+
+The `/stats` page's complete payload: totals, zero-filled daily arrays,
+streaks, most-active day, top books, and per-library/per-device breakdowns
+for a time range. All day boundaries and buckets are computed in the
+**requesting user's timezone**.
+
+## Query Parameters
+
+| Parameter | Type   | Required | Description                                        |
+| --------- | ------ | -------- | -------------------------------------------------- |
+| range     | string | No       | `7` (default), `30`, `90`, or `year` (days window) |
+
+Invalid `range` values return **400**.
+
+## Example Request
+
+```http
+GET /api/stats/summary?range=30
+Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
+```
+
+## Example response
+
+```json example-response
+{
+  "range": "30",
+  "days": 30,
+  "start_date": "2026-09-24",
+  "end_date": "2026-10-24",
+  "total_minutes": 1250,
+  "total_audio_minutes": 1100,
+  "total_pages": 412,
+  "session_count": 96,
+  "books_with_activity": 7,
+  "books_finished": 2,
+  "completion_rate": 0.29,
+  "average_session_minutes": 13.0,
+  "daily": [
+    {
+      "date": "2026-09-24",
+      "minutes": 42,
+      "pages": 15,
+      "sessions": 3,
+      "audio_minutes": 42
+    }
+  ],
+  "streak": { "current": 5, "longest": 12 },
+  "most_active_weekday": "Saturday",
+  "most_active_day": "2026-10-17",
+  "most_active_day_minutes": 87,
+  "top_books": [
+    {
+      "media_item_id": "550e8400-e29b-41d4-a716-446655440000",
+      "title": "Gardens of the Moon",
+      "author": "Steven Erikson",
+      "minutes": 610,
+      "pages": 0
+    }
+  ],
+  "library_breakdown": [
+    {
+      "library_id": "8c8d0cee-1cca-4def-9a37-edad3a4d438b",
+      "name": "Audiobooks",
+      "minutes": 1100,
+      "pages": 0,
+      "sessions": 84,
+      "books": 5
+    }
+  ],
+  "device_breakdown": [
+    { "device_id": "", "name": "Web", "type": "web", "minutes": 150 },
+    {
+      "device_id": "660e8400-e29b-41d4-a716-446655440001",
+      "name": "Pixel 9",
+      "type": "android",
+      "minutes": 1100
+    }
+  ]
+}
+```
+
+## Response fields
+
+| Field            | Type    | Notes                                                                 |
+| ---------------- | ------- | --------------------------------------------------------------------- |
+| total_audio_minutes | int  | listening minutes inside `total_minutes` (mode-aware wording surface) |
+| daily            | array   | zero-filled across the whole range — every day present                 |
+| streak           | object  | `current` / `longest` day streaks                                      |
+| most_active_weekday | string | `""` when the range has no sessions                                  |
+| device_breakdown | array   | `device_id` is `""` for the web bucket (pushes with no device credential) |
+
+## Errors
+
+| Status | Body                       | When                    |
+| ------ | -------------------------- | ----------------------- |
+| 400    | `invalid range ...`        | unknown range key       |
+| 401    | `invalid user`             | no user in JWT context  |