Add version numbering (v1.0.0)

- package.json: bump to 1.0.0
- server/config.js: export APP_VERSION (from package.json) and GIT_COMMIT
  (from COMMIT_SHA env var set by CI, or git rev-parse --short HEAD fallback)
- GET /api/version: new public endpoint returning { version, commit }
- GET /api/admin-auth/status: includes version and commit in response
- AdminPage sidebar: displays version string (e.g. "v1.0.0 (1d43875)")
  below the Log Out button, styled as muted metadata text

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/routes/admin-auth.js

@@ -1,6 +1,7 @@
 import rateLimit from 'express-rate-limit'
 import qrcode from 'qrcode'
 import { parseCookies } from '../helpers.js'
+import { APP_VERSION, GIT_COMMIT } from '../config.js'
 import {
   isAdminPasswordConfigured,
   isValidAdminSession,
@@ -40,6 +41,8 @@ export function register(app) {
       authenticated: isValidAdminSession(req),
       configured: isAdminPasswordConfigured(),
       totpEnabled: await isTotpEnabled(),
+      version: APP_VERSION,
+      commit: GIT_COMMIT,
     })
   })