Add Admin Recovery System with multiple backup options

- Recovery key generation (32-char alphanumeric, dashed format)
- Multiple backup methods: text file, QR code, stego image
- QR codes obfuscated with XOR (RECOVERY_OBFUSCATION_KEY constant)
- Stego backup hides key in image using Stegasoo itself
- CLI: `stegasoo admin recover --db path/to/db`
- Web routes: /recover, /account/recovery/regenerate
- Toast notifications now auto-dismiss after 20s with fade
- Updated WEB_UI.md and CLI.md documentation for v4.1.0

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontends/web/templates/login.html

@@ -38,6 +38,12 @@
                         <i class="bi bi-box-arrow-in-right me-2"></i>Login
                     </button>
                 </form>
+
+                <div class="text-center mt-3">
+                    <a href="{{ url_for('recover') }}" class="text-muted small">
+                        <i class="bi bi-key me-1"></i> Forgot password?
+                    </a>
+                </div>
             </div>
         </div>
     </div>