feat(analysis): page-analysis schema, domain types, and analyze_page job kind

Adds the persistence foundation for the AI content-analysis worker:

- Migration 0025: page_analysis (status + scene + is_nsfw + weighted
  search_doc tsvector), page_ocr_text (kind-tagged pieces), global
  page_auto_tags (shared tags vocabulary, separate from per-user
  page_tags), and page_content_warnings (closed vocabulary).
- domain::page_analysis: AnalysisStatus/OcrKind/ContentWarning enums with
  kind->tsvector-weight mapping and lenient model-string parsing, plus the
  VisionAnalysis response DTOs.
- JobPayload::AnalyzePage { page_id, force } + KIND_ANALYZE_PAGE, reusing
  the existing crawler_jobs queue.
- repo::page_analysis: enqueue_for_page, load, mark_failed, and the single
  transactional persist_analysis (delete+reinsert; idempotent; never
  touches user page_tags; computes the A/B/C/D-weighted search_doc).

Tests: repo integration (persist/idempotency/user-tags-untouched/enqueue/
mark_failed/speech>sfx ranking) + unit (weights, parsing, DTO, job serde).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/src/crawler/jobs.rs

@@ -34,6 +34,15 @@ pub enum JobPayload {
         chapter_id: Uuid,
         source_chapter_key: String,
     },
+    /// Run AI content-analysis (OCR, auto-tags, scene description, NSFW
+    /// moderation) on a single page image via the local vision model.
+    /// `force` re-analyzes a page that is already `done` (manual admin
+    /// re-trigger); otherwise the worker skips it.
+    AnalyzePage {
+        page_id: Uuid,
+        #[serde(default)]
+        force: bool,
+    },
 }
 
 #[derive(Clone, Copy, Debug, sqlx::Type, Serialize, Deserialize)]
@@ -52,6 +61,10 @@ pub enum JobState {
 /// without re-spelling the literal.
 pub const KIND_SYNC_CHAPTER_CONTENT: &str = "sync_chapter_content";
 
+/// Kind discriminator for AI page-analysis jobs. The analysis daemon
+/// leases with this filter so it never contends with crawl jobs.
+pub const KIND_ANALYZE_PAGE: &str = "analyze_page";
+
 #[derive(Debug)]
 pub enum EnqueueResult {
     Inserted(Uuid),
@@ -323,6 +336,29 @@ pub async fn reap_done(pool: &PgPool, retention_days: u32) -> sqlx::Result<u64>
 mod tests {
     use super::*;
 
+    #[test]
+    fn analyze_page_payload_round_trips_through_tagged_json() {
+        let page_id = Uuid::new_v4();
+        let payload = JobPayload::AnalyzePage {
+            page_id,
+            force: true,
+        };
+        let json = serde_json::to_value(&payload).unwrap();
+        assert_eq!(json["kind"], "analyze_page");
+        assert_eq!(json["page_id"], page_id.to_string());
+        assert_eq!(json["force"], true);
+
+        // `force` defaults to false when an older enqueue omitted it.
+        let legacy = serde_json::json!({ "kind": "analyze_page", "page_id": page_id });
+        match serde_json::from_value::<JobPayload>(legacy).unwrap() {
+            JobPayload::AnalyzePage { page_id: pid, force } => {
+                assert_eq!(pid, page_id);
+                assert!(!force);
+            }
+            other => panic!("expected AnalyzePage, got {other:?}"),
+        }
+    }
+
     #[test]
     fn backoff_base_grows_exponentially_and_caps_at_one_hour() {
         // attempts == 1 → 60s, doubling each step.