docs: update comprehensive API documentation and project guides

This commit updates all documentation files throughout the project:

- Updated IMPLEMENTATION_PLAN.md with new implementation details
- Updated PROJECT_GUIDELINES.md with coding standards and practices
- Updated README.md with current project information
- Updated SCREENSHOT_AUTOMATION.md with new automation details
- Added TEST_DATA.md with test fixtures data
- Updated cover_image_serving_plan.md with static URL patterns

Documentation API updates:
- Updated API reference documentation for all endpoints including:
  - Authentication (login, logout, register, refresh_token)
  - Book matching (auto_link, bulk_link, link_book, search)
  - Collections (CRUD operations, shelf mappings, auto-assign rules)
  - Conflicts (bulk operations, resolve/dismiss)
  - Devices (registration, approval, shelf management)
  - Highlights (create, update, delete, get)
  - Kobo sync (bookmark, markup, initialization, sync)
  - KOReader sync (library, metadata, bookmarks, progress)
  - Libraries (CRUD, folders, media items, stats)
  - Media items (bulk operations, CRUD)
  - Notes (CRUD operations)
  - OPDS (acquisition, feeds, publication)
  - Progress (reading progress tracking)
  - Queue (device queue management)
  - Ratings (star ratings)
  - Scanner (watch mode, scan operations)
  - Sync protocols (Kobo, KOReader)
  - Users (profile, password, admin operations)
  - WebSocket protocols

- Updated user guides (admin, dashboard, settings, sync)
- Updated device setup guides (Kobo, KOReader)
- Updated developer guides (testing, contributing, operations)
- Updated scripts/README.md

docs/developer/api/authentication/overview.md

@@ -42,6 +42,7 @@ When a user registers or logs in:
 4. Server returns JSON response with both tokens and user profile
 
 **Request**:
+
 ```json
 POST /api/auth/login
 {
@@ -51,6 +52,7 @@ POST /api/auth/login
 ```
 
 **Response**:
+
 ```json
 {
   "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
@@ -67,6 +69,7 @@ POST /api/auth/login
 ```
 
 **Set-Cookie Header**:
+
 ```
 Set-Cookie: token=eyJhbG...; Max-Age=604800; Path=/; HttpOnly
 ```
@@ -94,6 +97,7 @@ POST /api/auth/refresh
 ```
 
 **Response**:
+
 ```json
 {
   "access_token": "new-jwt-token",
@@ -135,6 +139,7 @@ When an API call receives a 401 Unauthorized response:
 ```
 
 The frontend toast.js interceptor:
+
 1. Clears invalid tokens from localStorage
 2. Shows an error toast notification
 3. Allows user to re-authenticate
@@ -149,10 +154,12 @@ The frontend toast.js interceptor:
 ## Token Storage Recommendations
 
 ### Browser Applications
+
 - **Backend**: Automatically manages HTTP-only cookie
 - **Frontend**: Store tokens in localStorage for API calls
 
 ### Mobile Applications
+
 - Store access token in secure storage (Keychain/Keystore)
 - Store refresh token in secure storage
 - Handle 401 responses by prompting user to re-authenticate
@@ -160,6 +167,7 @@ The frontend toast.js interceptor:
 ## Constants Reference
 
 All session durations use constants defined in:
+
 - `internal/handlers/auth.go` - SessionDuration, SessionDurationSec
 - `internal/handlers/refresh_token.go` - SessionDurationSec (mirrored)