feat(auth): Self-Service-Admin-Password-Reset via CLI-Token

Operator hat Admin-Passwort vergessen aber SSH-Zugang zur Box →
schneller Reset ohne SMTP/Email-Setup.

Flow:
  1. `sudo edgeguard-ctl reset-password` auf der Box → 32-hex-Token
     + ISO-Expiry werden nach /var/lib/edgeguard/.reset-token (mode
     0600 edgeguard:edgeguard) geschrieben, Token kommt auf stdout.
     TTL: 30 min.
  2. Login-Seite hat „Passwort vergessen?"-Link → /reset-password.
  3. Reset-Page: Token + neues Passwort (min. 12). POST /auth/reset-
     password validiert Token (constant-time compare), prüft Expiry,
     löscht das File (single-use), hash't das Passwort + speichert
     in setup.json.

internal/services/setup/:
  - SetAdminPassword() — bcrypt-hash + save, fehler wenn setup nicht
    completed
  - GenerateResetToken() / ConsumeResetToken() — File-basiert,
    Format: "<token>|<RFC3339-expiry>"

internal/handlers/auth.go: POST /api/v1/auth/reset-password.
cmd/edgeguard-ctl/main.go: `reset-password` command.

UI: /reset-password Page mit Info-Alert für CLI-Snippet
(„sudo edgeguard-ctl reset-password" im dunklen Code-Block); Login-
Seite bekommt den „Passwort vergessen?"-Link.

Verifiziert auf 1.0.76: CLI druckt Token + schreibt File mit 0600
edgeguard:edgeguard.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

management-ui/src/i18n/locales/en/common.json

@@ -172,7 +172,22 @@
     "login": "Sign in",
     "logout": "Sign out",
     "loginFailed": "Sign-in failed",
-    "loggedInAs": "Signed in as"
+    "loggedInAs": "Signed in as",
+    "forgotPassword": "Forgot your password?"
+  },
+  "reset": {
+    "title": "Reset admin password",
+    "intro": "Self-service reset via CLI token. You need SSH access to the box.",
+    "cliTitle": "1. Run on the box:",
+    "token": "Reset token",
+    "tokenExtra": "32 hex chars from the CLI output. Token is valid for 30 minutes.",
+    "newPassword": "New password (min. 12 chars)",
+    "confirmPassword": "Confirm password",
+    "submit": "Set password",
+    "backToLogin": "← Back to sign-in",
+    "mismatch": "Passwords don't match",
+    "success": "Password set. Redirecting…",
+    "failed": "Reset failed"
   },
   "setup": {
     "title": "First-time setup",