fix(publish): prevent stuck publish queue and duplicate posting

The desktop publish queue could stall for a long time and end users assumed
the software was broken. Root cause: a hung adapter held its execution slot
with no wall-clock timeout while auto-renewing its lease forever, so the
server never reclaimed it and every queued task behind it stayed 等待发布.
Auto-recovery also risked silently re-posting a non-idempotent article.

Client (Electron):
- per-task wall-clock deadline + abort; progress-gated lease renewal that
  stops and aborts a stalled task instead of renewing it forever
- decouple the concurrency cap from CDP-induced CPU/memory pressure
  (admission gate instead of self-throttling collapse); 15s watchdog pump
- all adapter network I/O now has fetch timeouts and honors context.signal;
  bounded image-upload concurrency with per-image timeout
- surface live adapter progress, elapsed time, queue position and a
  working-vs-queued distinction in the publish view

Server (tenant-api):
- publish lease-recovery worker (every 3m) + supporting index: reclaim
  expired in_progress publish leases, requeue (<3 attempts) or terminal-fail
- 3-minute lease TTL with client-presence-gated extension; max 3 attempts

Idempotency (production-grade core):
- durable publish_submit_started_at marker, set before the irreversible
  platform submit POST; recovery and abort route a maybe-submitted task to
  unknown (manual reconcile, kept in the dedup set) instead of re-posting
- desktop UI requires explicit confirmation before retrying a possibly-
  already-published task

Verified: go build/vet/test (incl. resolvePublishRecoveryOutcome), vue-tsc,
vitest 141/141, gofmt all clean.

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

server/migrations/20260530100000_add_publish_task_lease_recovery_index.down.sql

@@ -0,0 +1 @@
+DROP INDEX CONCURRENTLY IF EXISTS idx_desktop_tasks_publish_lease_recovery;

server/migrations/20260530100000_add_publish_task_lease_recovery_index.up.sql

@@ -0,0 +1,5 @@
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_desktop_tasks_publish_lease_recovery
+    ON desktop_tasks (lease_expires_at ASC, updated_at ASC, desktop_id ASC)
+    WHERE kind = 'publish'
+      AND status = 'in_progress'
+      AND lease_expires_at IS NOT NULL;

server/migrations/20260530101000_add_desktop_task_publish_submit_marker.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE desktop_tasks
+    DROP COLUMN IF EXISTS publish_submit_started_at;

server/migrations/20260530101000_add_desktop_task_publish_submit_marker.up.sql

@@ -0,0 +1,6 @@
+-- Durable "submit started" intent marker for desktop publish tasks.
+-- Set immediately before the irreversible platform submit POST so lease-recovery can tell
+-- "definitely not submitted yet" (safe to auto-requeue) apart from "may already be published"
+-- (route to 'unknown' / manual reconcile and never silently re-post a non-idempotent article).
+ALTER TABLE desktop_tasks
+    ADD COLUMN IF NOT EXISTS publish_submit_started_at TIMESTAMPTZ;