refactor(core): overhaul state transition architecture, persistent job queue, and API layer

- Implement atomic state transitions: add EntryService.PatchEntry() with EntryDiff computation and EventEntryTransition event emission.
- Add persistent SQLite task queue (JobEngine): add jobs table with crash recovery, exponential backoff retries, concurrency control, and idempotency key deduplication.
- Decompose monolithic HTTP handlers: split handlers.go into domain handlers (auth, feeds, entries, jobs, settings, rules, sse).
- Implement real-time Server-Sent Events (/api/events/stream) for multi-tab/device state synchronization.
- Fix SQLite concurrency: apply busy_timeout(10000) and journal_mode(WAL) via DSN query parameters to resolve SQLITE_BUSY (5).
- Fix AI settings & prompt loading: unmarshal JSON from ai_settings, apply configured prompt templates, and enforce strict enabled/API key validations.
- Fix undo share state: remove omitempty from ShareUUID to serialize null for state resets.
- Fix middle list counter: compute true unread/total stats from DB and clean switcher button labels.
- Adapt mobile UI for iOS: add viewport-fit=cover in index.html and calibrate safe-area insets for the bottom navigation and article reader toolbar.
- Add architectural documentation and worklog in docs/009_worklog.md.

internal/crawler/crawler.go

@@ -202,15 +202,27 @@ func (c *Crawler) fetchSingleFeed(ctx context.Context, f models.Feed) error {
 			zap.Int("new_entries", len(newEntries)),
 		)
 
-		// Publish on_post_created events for newly inserted entries
+		// Publish on_post_created and on_entry_transition events for newly inserted entries
 		if c.bus != nil {
 			for _, entry := range newEntries {
 				entry.FeedTitle = f.Title
 				entry.FeedSiteURL = f.SiteURL
+				diff := &models.EntryDiff{
+					FieldsChanged: []string{"id", "title", "content", "url"},
+				}
 				c.bus.Publish(ctx, events.Event{
-					Type:  events.EventPostCreated,
-					Entry: entry,
-					Depth: 0,
+					Type:     events.EventPostCreated,
+					Entry:    entry,
+					NewEntry: &entry,
+					Diff:     diff,
+					Depth:    0,
+				})
+				c.bus.Publish(ctx, events.Event{
+					Type:     events.EventEntryTransition,
+					Entry:    entry,
+					NewEntry: &entry,
+					Diff:     diff,
+					Depth:    0,
 				})
 			}
 		}