feat(devices): camera clock sync via ISAPI — heal the 1970 power-cut reset

park-buzi field observation: after a power cut the Hikvision cameras
reboot at the 1970 epoch (no/dead RTC battery, no NTP) and stay there
until a human logs into the web UI (which silently pushes the browser
clock) — corrupting the snapshot OSD timestamps (the evidence trail) and
ANPR push times meanwhile.

The host is the site's time authority (offline-first, no NTP infra):

- Device monitor triggers a sync at each camera's offline→ready edge —
  exactly the power-restored moment — plus a 24h backstop; the attempt
  is stamped before the async call so a failing camera retries at
  backstop cadence, never every poll.
- HikvisionCamera.syncClock: GET /ISAPI/System/time; drift ≤60s → leave
  alone; beyond (or unparseable = infinite drift) → PUT timeMode=manual
  with the site wall-clock now WITH explicit utc offset
  (localIsoWithOffset), echoing the camera's timeZone verbatim — correct
  the clock, never fight its tz/DST config.
- Jumps >1h (the power-cut signature) log warn (persisted to app_logs);
  small corrections info. Capability-guarded (isClockSyncable) —
  hikvision only; dahua's CGI has no such endpoint.
- http-digest generalised to digestRequest (GET/PUT/POST + body); the
  handshake was already method-aware. digestGet delegates unchanged.

8 new tests: in-sync no-op, 1970 PUT shape (manual + host instant +
echoed tz), unparseable→sync, failed-set surfaces, dahua non-capability,
DST-both-sides pins on the offset formatter.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

wiki/log.md

@@ -2505,3 +2505,14 @@ GET /api/setup/usb-printers enumerates /dev/usb/lpN + sysfs ieee1284_id make/mod
 devicePath is now a select of PRESENT printers (fresh form preselects the first; a saved-but-
 absent path stays selectable, flagged; none found → free-text + hint). Transport option label no
 longer hardcodes lp0. Details on [[printer-usb-transport]].
+
+## [2026-07-07] update | Camera clock sync via ISAPI — the 1970 power-cut reset healed
+
+park-buzi observation: power-cut Hik cameras reboot at the 1970 epoch (no RTC battery, no NTP)
+until a web-UI login pushes the browser clock — corrupting snapshot OSD timestamps (evidence) and
+ANPR push times meanwhile. Built host-as-time-authority sync (details on [[lpr-camera]] §Clock
+sync): device monitor triggers at the offline→ready edge + 24h backstop; HikvisionCamera.syncClock
+GETs /ISAPI/System/time, and beyond 60s drift PUTs manual time with the site's wall-clock + explicit
+offset, echoing the camera's timeZone verbatim; >1h jumps log warn (persisted). digest client
+generalised GET→GET/PUT/POST with body (the handshake was already method-aware). Capability-guarded
+(isClockSyncable — hikvision only). 8 new tests (5 devices, 3 tz-offset).