Add multi-user web server variant (browser UI behind a reverse proxy)

New web/ subfolder: a Node http server that serves the SAME tooling as the
Electron app to any browser, with per-session MCMS credentials so several
operators can use it at once behind a TLS reverse proxy. Mobile-responsive.

Not a fork — it reuses the core and the UI:
- serves renderer/app.js + app.css verbatim and rewrites index.html on the
  fly (mobile viewport + browser window.api shim + responsive overlay)
- web/public/api-web.js: a drop-in window.api over fetch + NDJSON streaming;
  Electron file dialogs -> <input type=file>, CSV-to-Downloads -> Blob
- web/server.js: per-session McmsClient (cookie pfw_sid), idle expiry,
  routes mirroring the IPC handlers, NDJSON for the 6 streaming ops
- pure Node http, no new deps (borrows ../node_modules tough-cookie)

Shared improvements (benefit both apps):
- src/dashboard.js: extracted, pure dashboard aggregation (main.js now uses
  it); adds abnormal-Tx detection alongside abnormal-Rx
- renderer: dashboard health stats are now clickable — abnormal Rx / Tx /
  lasers-off pop a list of the offending devices (like the iOS app), via a
  new showListModal

Docs: web/README.md (run + reverse-proxy + security), CLAUDE.md §16.

Verified: node --check all; started the server and confirmed transformed
index, shared-asset serving, 401 auth gate, login (per-session client), and
NDJSON wiring; rendered login + dashboard drilldown + mobile over HTTP.

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

web/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "pon-fleet-web",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Multi-user, reverse-proxy-friendly web server for the PON fleet tools. Reuses ../src core and ../renderer UI; per-session MCMS credentials.",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js",
+    "check": "node --check server.js && node --check public/api-web.js"
+  },
+  "license": "UNLICENSED"
+}