Phase 3: VISUAL feed and M-Files drawings in the worker

Migration 0004 (VISUAL and drawing caches, go-live ignored list, resource
map, job tables, order-derived columns with provenance; work order key
includes the operation sequence). The real worker on APScheduler with
settings re-read each fire, pause, run now, advisory locks, job_runs and a
heartbeat. The visual-feed job (five VisualKit reads, COPY and MERGE cache,
suspect-batch guard, the apply in one transaction: drafts, change orders,
retire-moved, work order gone, closed and cancelled observed, projects and
units from order links, auto-release) and the fingerprint. The drawing-lookup
job (queue, budget, download on version change, sha256 into assets, decision
table, staging for rev approval, drawing-origin change orders). Clerical From
VISUAL panel, flags, rev approval, hand uploads, change-order review; Admin
Feed settings and resource map. Synthetic fixture generator and a
fixture-driven worker in CI with a Playwright scenario. Docs updated.

Verified: 3249 server tests and 13 Playwright scenarios on the docker-1 CI
stack, 76 frontend tests, doctor at 0004; one feed and one drawing run
against VISUAL DEV and the vault from the developer machine (counts in the
changelog).

Co-Authored-By: Claude Fable 5.1 <[email protected]>

server/packetstation/worker/heartbeat.py

@@ -0,0 +1,36 @@
+"""The worker's heartbeat: a touched beat file for the container healthcheck and a worker_heartbeat row."""
+
+from __future__ import annotations
+
+import os
+import time
+from collections.abc import Iterable
+from pathlib import Path
+from typing import Any
+
+BEAT_SECONDS = 30
+STALE_SECONDS = 90
+
+
+def touch(path: Path) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.touch(exist_ok=True)
+    now = time.time()
+    os.utime(path, (now, now))
+
+
+def beat_age(beat_file: Path) -> float | None:
+    try:
+        return time.time() - beat_file.stat().st_mtime
+    except OSError:
+        return None
+
+
+def write_row(conn: Any, *, build: str, host: str, pid: int, running: Iterable[str]) -> None:
+    """Upsert the single worker_heartbeat row."""
+    conn.execute(
+        "INSERT INTO worker_heartbeat (id, at, build, host, pid, running) VALUES (1, now(), %s, %s, %s, %s)"
+        " ON CONFLICT (id) DO UPDATE SET at = EXCLUDED.at, build = EXCLUDED.build, host = EXCLUDED.host,"
+        " pid = EXCLUDED.pid, running = EXCLUDED.running",
+        (build, host, pid, sorted(running)),
+    )