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>

app/modules/chat_room/schemas.py

@@ -83,7 +83,7 @@ class RoomFilterParams(BaseModel):
     created_after: Optional[datetime] = None
     created_before: Optional[datetime] = None
     search: Optional[str] = Field(None, description="Search in title and description")
-    all: Optional[bool] = Field(False, description="Admin: show all rooms")
+    my_rooms: Optional[bool] = Field(False, description="Filter to show only rooms where user is a member")
     limit: int = Field(20, ge=1, le=100)
     offset: int = Field(0, ge=0)
 
@@ -122,6 +122,7 @@ class RoomResponse(BaseModel):
     member_count: int
     members: Optional[List[MemberResponse]] = None
     current_user_role: Optional[MemberRole] = None
+    is_member: bool = False
     is_admin_view: bool = False
 
     class Config: