feat(database): add analytics and book matching queries

Add analytics queries:
- GetUserReadingHistory: detailed reading history with device info
- GetUserDeviceUsage: device usage statistics (sync count, time spent)
- GetPopularBooks: most read books with completion rates

Add book matching queries:
- GetUnlinkedBookByID: fetch single unlinked book
- DeleteUnlinkedBook: remove resolved unlinked book
- ListUnresolvedUnlinkedBooks: paginated list of unresolved books

internal/database/queries/queries.sql

@@ -627,7 +627,66 @@ INSERT INTO reading_history (
 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
 RETURNING *;
 
--- ============================================
+-- Analytics queries
+
+-- Get user reading history for analytics
+-- name: GetUserReadingHistory :many
+SELECT
+    rh.id,
+    rh.user_id,
+    rh.media_item_id,
+    rh.device_id,
+    rh.progress_percentage,
+    rh.reading_session_start,
+    rh.reading_session_end,
+    rh.pages_read,
+    rh.time_spent_seconds,
+    rh.device_metadata,
+    rh.created_at,
+    mi.title,
+    mi.author,
+    d.device_name,
+    d.device_type
+FROM reading_history rh
+JOIN media_items mi ON rh.media_item_id = mi.id
+LEFT JOIN devices d ON rh.device_id = d.id
+WHERE rh.user_id = $1
+  AND rh.created_at >= $2
+  AND rh.created_at <= $3
+ORDER BY rh.created_at DESC;
+
+-- Get user device usage statistics
+-- name: GetUserDeviceUsage :many
+SELECT
+    d.id,
+    d.device_name,
+    d.device_type,
+    COUNT(*) as sync_count,
+    MAX(rh.created_at) as last_sync,
+    SUM(rh.time_spent_seconds) as total_time_seconds
+FROM devices d
+JOIN reading_history rh ON rh.device_id = d.id
+WHERE d.user_id = $1
+GROUP BY d.id, d.device_name, d.device_type
+ORDER BY sync_count DESC;
+
+-- Get most popular books for a user
+-- name: GetPopularBooks :many
+SELECT
+    mi.id,
+    mi.title,
+    mi.author,
+    COUNT(*) as read_count,
+    AVG(rh.progress_percentage) as avg_completion,
+     MAX(rh.created_at) as last_read
+ FROM media_items mi
+ JOIN reading_history rh ON rh.media_item_id = mi.id
+ WHERE rh.user_id = $1
+ GROUP BY mi.id, mi.title, mi.author
+ ORDER BY read_count DESC
+ LIMIT $2;
+
+ -- ============================================
 -- PHASE 2: DEVICE MANAGEMENT & AUTH (Weeks 5-6)
 -- ============================================
 
@@ -818,12 +877,19 @@ RETURNING *;
 -- name: DeleteSyncConflict :exec
 DELETE FROM sync_conflicts WHERE id = $1;
 
--- name: ListAllConflictsByUserAndStatus :many
-SELECT sc.*, mi.title, mi.author
-FROM sync_conflicts sc
-JOIN media_items mi ON sc.media_item_id = mi.id
-WHERE sc.user_id = $1 AND sc.resolution_status = $2
-ORDER BY sc.created_at DESC;
+ -- name: ListAllConflictsByUserAndStatus :many
+ SELECT sc.*, mi.title, mi.author
+ FROM sync_conflicts sc
+ JOIN media_items mi ON sc.media_item_id = mi.id
+ WHERE sc.user_id = $1 AND sc.resolution_status = $2
+ ORDER BY sc.created_at DESC;
+
+ -- name: ListConflictsByUser :many
+ SELECT sc.*, mi.title, mi.author
+ FROM sync_conflicts sc
+ JOIN media_items mi ON sc.media_item_id = mi.id
+ WHERE sc.user_id = $1
+ ORDER BY sc.created_at DESC;
 
 -- ============================================
 -- PHASE 3: KOREADER SYNC PROTOCOL (Weeks 7-9)
@@ -1467,4 +1533,21 @@ SET
     resolved_at = NOW(),
     resolution_method = 'manual_link'
 WHERE id = $1
-RETURNING *;
+RETURNING *;
+
+-- Get unlinked book by ID
+-- name: GetUnlinkedBookByID :one
+SELECT * FROM unlinked_books WHERE id = $1;
+
+-- Delete unlinked book
+-- name: DeleteUnlinkedBook :exec
+DELETE FROM unlinked_books WHERE id = $1;
+
+-- List unresolved unlinked books with pagination
+-- name: ListUnresolvedUnlinkedBooks :many
+SELECT ub.*, d.device_name, d.device_type
+FROM unlinked_books ub
+JOIN devices d ON ub.device_id = d.id
+WHERE ub.resolved = false
+ORDER BY ub.last_seen_at DESC
+LIMIT $1 OFFSET $2;