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/rules/rules_test.go

@@ -116,3 +116,73 @@ func TestRuleEvaluator(t *testing.T) {
 		t.Error("expected ValidateRuleSafety to detect cyclic loop")
 	}
 }
+
+func TestTransitionEvaluation(t *testing.T) {
+	eval := NewEvaluator()
+
+	oldEntry := models.FeedEntry{
+		ID:        "entry-2",
+		FeedID:    "feed-1",
+		FeedTitle: "Tech Blog",
+		Title:     "Deep Dive into Go Scheduler",
+		Content:   "Short intro...",
+		Variants:  map[string]models.EntryVariant{},
+	}
+
+	newEntryWithFullText := models.FeedEntry{
+		ID:        "entry-2",
+		FeedID:    "feed-1",
+		FeedTitle: "Tech Blog",
+		Title:     "Deep Dive into Go Scheduler",
+		Content:   "Short intro...",
+		Variants: map[string]models.EntryVariant{
+			"readability_full_text": {
+				EntryID:    "entry-2",
+				VariantKey: "readability_full_text",
+				TextValue:  "Full article content here with extensive details...",
+			},
+		},
+	}
+
+	diff := &models.EntryDiff{
+		VariantsAdded: []string{"readability_full_text"},
+	}
+
+	// Rule: trigger AI summary when readability_full_text became_present AND ai_summary is empty
+	aiRule := models.Rule{
+		ID:        "r-ai",
+		Name:      "AI summary on full text added",
+		MatchMode: "all",
+		Conditions: []models.RuleCondition{
+			{Field: "variants.readability_full_text", Operator: "became_present"},
+			{Field: "variants.ai_summary", Operator: "is_empty"},
+		},
+	}
+
+	// Should match when full text was added
+	if !eval.EvaluateTransition(aiRule, &oldEntry, &newEntryWithFullText, diff) {
+		t.Error("expected aiRule to match when readability_full_text became_present")
+	}
+
+	// Should NOT match if tag was added instead of full text
+	diffOnlyTags := &models.EntryDiff{
+		FieldsChanged: []string{"metadata.tags"},
+	}
+	if eval.EvaluateTransition(aiRule, &oldEntry, &oldEntry, diffOnlyTags) {
+		t.Error("expected aiRule to NOT match when only tags changed")
+	}
+
+	// Test word count condition for TTS: word_count >= 5
+	ttsRule := models.Rule{
+		ID:        "r-tts",
+		Name:      "TTS on long summary",
+		MatchMode: "all",
+		Conditions: []models.RuleCondition{
+			{Field: "variants.readability_full_text.word_count", Operator: ">=", Value: 5},
+		},
+	}
+
+	if !eval.EvaluateTransition(ttsRule, &oldEntry, &newEntryWithFullText, diff) {
+		t.Error("expected ttsRule to match when word_count >= 5")
+	}
+}