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/api/jobs_handler.go

@@ -0,0 +1,70 @@
+package api
+
+import (
+	"database/sql"
+	"net/http"
+	"strconv"
+
+	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
+	"github.com/go-chi/chi/v5"
+)
+
+func (h *Handler) ListJobs(w http.ResponseWriter, r *http.Request) {
+	q := r.URL.Query()
+	limit, _ := strconv.Atoi(q.Get("limit"))
+	offset, _ := strconv.Atoi(q.Get("offset"))
+
+	filter := models.JobFilter{
+		Type:   q.Get("type"),
+		Status: q.Get("status"),
+		Limit:  limit,
+		Offset: offset,
+	}
+
+	jobs, err := h.jobService.ListJobs(r.Context(), filter)
+	if err != nil {
+		h.writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if jobs == nil {
+		jobs = []models.Job{}
+	}
+
+	h.writeJSON(w, http.StatusOK, map[string]interface{}{
+		"jobs":   jobs,
+		"limit":  limit,
+		"offset": offset,
+	})
+}
+
+func (h *Handler) GetJob(w http.ResponseWriter, r *http.Request) {
+	id := chi.URLParam(r, "id")
+	job, err := h.jobService.GetJob(r.Context(), id)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			h.writeError(w, http.StatusNotFound, "job not found")
+			return
+		}
+		h.writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	h.writeJSON(w, http.StatusOK, job)
+}
+
+func (h *Handler) CancelJob(w http.ResponseWriter, r *http.Request) {
+	id := chi.URLParam(r, "id")
+	if err := h.jobService.CancelJob(r.Context(), id); err != nil {
+		h.writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	h.writeJSON(w, http.StatusOK, map[string]string{"message": "job cancelled"})
+}
+
+func (h *Handler) RetryJob(w http.ResponseWriter, r *http.Request) {
+	id := chi.URLParam(r, "id")
+	if err := h.jobService.RetryJob(r.Context(), id); err != nil {
+		h.writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	h.writeJSON(w, http.StatusOK, map[string]string{"message": "job queued for retry"})
+}