onu detail: parent OLT + LLDP switch + traffic history + alarms + UNI; single-ONU upgrade

De-compacts the ONU info page into a responsive card grid and enriches it
with one new endpoint (api:getOnuDetail) summarized by the pure, shared
src/onudetail.js:
- Parent OLT (name/model/FW/PON) — follows the OLT MAC from the ONU
  alarm-history doc to its OLT-CFG.
- Upstream switch (LLDP neighbour of the OLT NNI) from the alarm-history
  Switch block: system name, port, IPv4, chassis.
- Traffic (last ~hour) with current + peak down/up and inline SVG
  sparklines, from /onus/stats/ (down = OLT TX rate, up = OLT RX rate).
- UNI-ETH ports (speed/duplex/enable) + last Ethernet LOS (LAN-LOS alarm).
- Alarms: active-first, severity-sorted with raised counts + last raised.
- CPE card folded into the same single fetch.

New client methods getOnuAlarms + getOnuStatsSeries; api:getOnuDetail in
main.js + web/server.js, exposed in both bridges. Not TTL-cached (live).

Single-ONU upgrade: the Firmware card gets a firmware picker + "Upgrade this
ONU" button reusing the bulk per-ONU path (executePerOnu with one id,
Procedure 7 inactive-bank write), behind a typed UPGRADE confirm; refreshes
the detail on success.

Docs: CLAUDE.md §17 + §5.11 (stats endpoint now used for the sparkline) +
IPC table.

Verified: node --check; onudetail.js unit-tested 11/11 against the real
alarm-history / cfg / stats / OLT-cfg fixtures (firmware banks, UNI, alarm
sort, LAN-LOS, OLT active-bank FW, LLDP switch, traffic skip-nontraffic +
down/up mapping + current/peak); card grid rendered offscreen (9 cards, 2
sparklines, upgrade button).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/public/api-web.js

@@ -148,6 +148,7 @@
     fetchStates: (o) => streamJSON('fetchStates', o, 'states'),
     getOnuConfig: (o) => postJSON('getOnuConfig', o),
     getOnuCpe: (o) => postJSON('getOnuCpe', o),
+    getOnuDetail: (o) => postJSON('getOnuDetail', o),
     listOnuFirmware: () => postJSON('listOnuFirmware', {}),
     uploadFirmware: async () => {
       const file = await pickFile('.bin');