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/services/entry_service_test.go

@@ -0,0 +1,85 @@
+package services
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"git.pengzhan.dev/haopengzhan/rsspipe/internal/db"
+	"git.pengzhan.dev/haopengzhan/rsspipe/internal/events"
+	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
+)
+
+func TestEntryServicePatchAndTransition(t *testing.T) {
+	tempDBPath := filepath.Join(t.TempDir(), "test.db")
+	database, err := db.InitDB(tempDBPath)
+	if err != nil {
+		t.Fatalf("failed to init db: %v", err)
+	}
+	defer func() { _ = database.Close() }()
+
+	bus := events.NewEventBus()
+	svc := NewEntryService(database, bus)
+
+	// Create test category and feed
+	cat, _ := database.CreateCategory("Tech", nil)
+	feed, _ := database.CreateFeed("Test Feed", "https://example.com/rss", "https://example.com", "", &cat.ID)
+
+	// Ingest an entry
+	entry := models.FeedEntry{
+		ID:          "e_test_1",
+		FeedID:      feed.ID,
+		GUID:        "guid_1",
+		URL:         "https://example.com/p/1",
+		Title:       "Test Post",
+		Content:     "Hello world",
+		PublishedAt: time.Now().UTC(),
+	}
+
+	ingested, err := svc.IngestEntries(context.Background(), feed.ID, []models.FeedEntry{entry}, feed.Title, feed.SiteURL)
+	if err != nil || len(ingested) == 0 {
+		t.Fatalf("failed to ingest entry: %v", err)
+	}
+
+	// 1. Test patching tags
+	isStarred := true
+	updated, diff, err := svc.PatchEntry(context.Background(), ingested[0].ID, models.PatchEntryRequest{
+		IsStarred: &isStarred,
+		Metadata: map[string]interface{}{
+			"tags": []string{"AI", "Kubernetes"},
+		},
+	})
+	if err != nil {
+		t.Fatalf("failed to patch entry: %v", err)
+	}
+
+	if !updated.IsStarred {
+		t.Errorf("expected entry to be starred")
+	}
+	if !diff.HasFieldChange("is_starred") {
+		t.Errorf("expected diff to contain is_starred change")
+	}
+
+	// 2. Test patching variant addition (readability_full_text)
+	fullTextVariant := &models.EntryVariant{
+		ContentType: "html",
+		TextValue:   "<p>Full article extracted content...</p>",
+	}
+
+	updated2, diff2, err := svc.PatchEntry(context.Background(), ingested[0].ID, models.PatchEntryRequest{
+		Variants: map[string]*models.EntryVariant{
+			"readability_full_text": fullTextVariant,
+		},
+	})
+	if err != nil {
+		t.Fatalf("failed to patch variant: %v", err)
+	}
+
+	if !diff2.HasVariantAddition("readability_full_text") {
+		t.Errorf("expected diff2 to report variant addition of readability_full_text")
+	}
+	if updated2.Variants["readability_full_text"].TextValue == "" {
+		t.Errorf("expected variant to be loaded in updated entry")
+	}
+}