feat: base64 uploads, reusable forms, Discord roles, and UX improvements (#66)

## Summary

This PR includes multiple feature additions and fixes to improve the library application:

### 🎨 Base64 Image Upload Support
- Fixed Fastify body limit (1MB → 10MB) to accommodate base64-encoded images
- Corrected base64 size calculation and validation logic
- Improved error handling with proper 400 status codes and helpful messages
- Removed duplicate validation that was blocking uploads
- Users can now upload cover images up to 5MB (decoded size)

### 📝 Reusable Form Components
- Created 6 form components: `GameForm`, `BookForm`, `MusicForm`, `ShowForm`, `MangaForm`, `ArtForm`
- All forms support both 'add' and 'edit' modes with pre-population
- Integrated inline editing into all detail views (edit/delete buttons)
- Enhanced admin suggestions workflow with full forms instead of basic modals
- Added scroll-to-top when clicking edit in list views for better UX

### 🖼️ Default Cover Image
- Added beautiful library reading image as default cover for all media types
- Fixed static asset serving to use correct MIME types
- Updated all 12 components (6 list views + 6 detail views) to always show images

### 🔒 Tiered Rate Limiting
- Unauthenticated users: 100 requests/minute
- Authenticated users: 500 requests/minute (5x more lenient)
- Admin users: No rate limits (complete bypass via allowList)

### 🎮 Discord Integration
- Auto-assign library member role to users in NHCarrigan Discord server
- Checks server membership on every login
- Only assigns role if user is in server and doesn't have it yet
- Graceful error handling without blocking login
- Similar pattern to badge refresh flow

### 📚 Documentation
- Added comprehensive CLAUDE.md with:
  - Project structure and tech stack
  - Development workflow and commands
  - Database schema documentation
  - Authentication flow details
  - Security features
  - Code style conventions
  - Common gotchas and solutions

## Test Plan

- [x] Base64 image uploads work for cover images up to 5MB
- [x] Helpful error messages appear for validation failures
- [x] Edit/delete buttons appear on all detail views for admin users
- [x] Inline edit forms display and save correctly
- [x] Admin suggestions workflow uses full forms for all media types
- [x] Scroll-to-top works when editing from list views
- [x] Default cover image displays when no cover is provided
- [x] Static assets serve with correct MIME types
- [x] Rate limiting works correctly for different user types
- [x] Discord role assignment works on login
- [x] All builds pass without errors
- [x] No TypeScript errors

## Related Issues

Closes #65 - Base64 image upload issue

✨ This pull request was created with help from Hikari~ 🌸

Reviewed-on: #66
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

apps/frontend/src/app/components/games/games-list.component.ts

@@ -625,9 +625,7 @@ import { Game, GameStatus, CreateGameDto, UpdateGameDto, Comment, SuggestionEnti
           @for (game of paginatedGames(); track game.id) {
             <div class="game-card" [class.completed]="game.status === GameStatus.completed">
               <a [routerLink]="['/games', game.id]" class="card-link">
-                @if (game.coverImage) {
-                  <img [src]="game.coverImage" [alt]="game.title" class="game-cover">
-                }
+                <img [src]="game.coverImage || '/assets/default-cover.jpg'" [alt]="game.title" class="game-cover">
 
                 <div class="game-info">
                   <h3>{{ game.title }}</h3>
@@ -1434,6 +1432,9 @@ export class GamesListComponent implements OnInit {
     this.editTagInput = '';
     this.editLinkTitle = '';
     this.editLinkUrl = '';
+
+    // Scroll to top so the form is visible
+    window.scrollTo({ top: 0, behavior: 'smooth' });
   }
 
   cancelEdit() {