feat: Add mobile responsive layout, open room access, and admin room management

Mobile Responsive Layout:
- Add useMediaQuery, useIsMobile, useIsTablet, useIsDesktop hooks for device detection
- Create MobileHeader component with hamburger menu and action drawer
- Create BottomToolbar for mobile navigation (Files, Members)
- Create SlidePanel component for full-screen mobile sidebars
- Update RoomDetail.tsx with mobile/desktop conditional rendering
- Update RoomList.tsx with single-column grid and touch-friendly buttons
- Add CSS custom properties for safe areas and touch targets (min 44px)
- Add mobile viewport meta tags for notched devices

Open Room Access:
- All authenticated users can view all rooms (not just their own)
- Users can join active rooms they're not members of
- Add is_member field to room responses
- Update room list API to return all rooms by default

Admin Room Management:
- Add permanent delete functionality for system admins
- Add delete confirmation dialog with room title verification
- Broadcast room deletion via WebSocket to connected users
- Add users search API for adding members

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

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

openspec/specs/frontend-core/spec.md

@@ -36,35 +36,26 @@ The frontend SHALL provide a login interface that authenticates users against th
   - Redirect to login page
 
 ### Requirement: Incident Room List
-The frontend SHALL display a filterable, searchable list of incident rooms accessible to the current user.
+The frontend SHALL display a filterable, searchable list of incident rooms accessible to the current user. The frontend SHALL restrict the status filter options to show only "Active" and "Resolved" for non-admin users, and SHALL display all status options including "Archived" only for system administrators.
 
-#### Scenario: Display room list
-- **WHEN** a logged-in user navigates to the room list page
+#### Scenario: Filter rooms by status (Non-admin)
+- **WHEN** a non-admin user views the status filter dropdown
 - **THEN** the system SHALL:
-  - Fetch rooms from `GET /api/rooms`
-  - Display rooms as cards with title, status, severity, and timestamp
-  - Show the user's role in each room
-  - Order by last activity (most recent first)
+  - Display only "Active" and "Resolved" options
+  - NOT display "Archived" option
+  - NOT display "All Status" option that would include archived rooms
 
-#### Scenario: Filter rooms by status
-- **WHEN** a user selects a status filter (Active, Resolved, Archived)
+#### Scenario: Filter rooms by status (Admin)
+- **WHEN** a system administrator views the status filter dropdown
 - **THEN** the system SHALL:
-  - Update the room list to show only rooms matching the filter
-  - Preserve other active filters
+  - Display all status options: "All Status", "Active", "Resolved", "Archived"
+  - Allow viewing archived rooms
 
-#### Scenario: Search rooms
-- **WHEN** a user enters text in the search box
+#### Scenario: Default status filter
+- **WHEN** a user navigates to the room list page
 - **THEN** the system SHALL:
-  - Filter rooms by title and description containing the search text
-  - Update results in real-time (debounced)
-
-#### Scenario: Create new room
-- **WHEN** a user clicks "New Room" and fills the creation form
-- **THEN** the system SHALL:
-  - Display template selection if templates exist
-  - Submit room creation to `POST /api/rooms`
-  - Navigate to the new room on success
-  - Show error message on failure
+  - Default to "Active" status filter for all users
+  - Fetch only active rooms initially
 
 ### Requirement: Incident Room Detail View
 The frontend SHALL display complete incident room information including metadata, members, and provide management controls for authorized users.
@@ -270,3 +261,43 @@ The frontend SHALL provide a responsive layout that works on desktop and tablet
   - Log error details for debugging
   - Not crash or show blank screen
 
+### Requirement: Admin Room Deletion Interface
+The frontend SHALL provide system administrators with the ability to permanently delete rooms through a dedicated UI control.
+
+#### Scenario: Display delete button for admin
+- **WHEN** a system administrator views a room detail page
+- **THEN** the system SHALL:
+  - Display a "Delete Room Permanently" button in room settings/actions
+  - Style the button with warning color (red)
+  - Only show this button to admin users
+
+#### Scenario: Hide delete button for non-admin
+- **WHEN** a non-admin user views a room detail page
+- **THEN** the system SHALL:
+  - NOT display permanent delete option
+  - Only show standard archive option (if owner)
+
+#### Scenario: Confirm permanent deletion
+- **WHEN** an admin clicks "Delete Room Permanently"
+- **THEN** the system SHALL:
+  - Display a confirmation dialog with warning text
+  - Require typing room name to confirm (optional safety measure)
+  - Explain that deletion is irreversible
+  - Show what will be deleted (messages, files, reports)
+
+#### Scenario: Execute permanent deletion
+- **WHEN** an admin confirms permanent deletion
+- **THEN** the system SHALL:
+  - Send DELETE request to `/api/rooms/{room_id}/permanent`
+  - Show loading state during deletion
+  - Navigate to room list on success
+  - Show success toast message
+  - Show error message on failure
+
+#### Scenario: Handle active users in deleted room
+- **WHEN** a room is permanently deleted while other users are viewing it
+- **THEN** the system SHALL:
+  - Receive WebSocket disconnect event
+  - Display "Room has been deleted" message
+  - Navigate affected users to room list
+