Add reading lists feature with pinning and management

Adds full support for book lists managed by the Companion App:
- New /list API endpoints (GET/POST) for uploading, retrieving, and deleting lists
- BookListStore for binary serialization of lists to /.lists/ directory
- ListViewActivity for viewing list contents with book thumbnails
- Reading Lists tab in My Library with pin/unpin and delete actions
- Pinnable list shortcut on home screen (split button layout)
- Automatic cleanup of pinned status when lists are deleted

docs/webserver-api-reference.md

@@ -181,6 +181,77 @@ Source: `src/network/CrossPointWebServer.cpp` and `CrossPointWebServer.h`
 - Falls back to copy+delete if rename fails
 - Uses `deleteFolderRecursive()` for folder cleanup
 
+### GET /list
+**Handler:** `handleListGet()`
+**Query params:**
+- `name` (optional): Specific list name to retrieve
+**Response:** JSON array of lists (if no name) or single list details (if name specified)
+**Content-Type:** application/json
+
+**Response (all lists - no name param):**
+```json
+[
+  {"name": "MyReadingList", "path": "/.lists/MyReadingList.bin", "bookCount": 5},
+  {"name": "Favorites", "path": "/.lists/Favorites.bin", "bookCount": 12}
+]
+```
+
+**Response (specific list - with name param):**
+```json
+{
+  "name": "MyReadingList",
+  "path": "/.lists/MyReadingList.bin",
+  "books": [
+    {"order": 1, "title": "The Great Gatsby", "author": "F. Scott Fitzgerald", "path": "/Books/gatsby.epub"},
+    {"order": 2, "title": "1984", "author": "George Orwell", "path": "/Books/1984.epub"}
+  ]
+}
+```
+
+**Errors:**
+- 404: List not found (when `name` specified but doesn't exist)
+
+**Notes:**
+- Lists are stored in `/.lists/` directory as `.bin` files
+- Uses `BookListStore::listAllLists()` and `BookListStore::loadList()`
+
+### POST /list
+**Handler:** `handleListPost()`
+**Query params:**
+- `action` (required): "upload" or "delete"
+- `name` (required): List name (without .bin extension)
+**Request body (for upload):** CSV text with one book per line
+**Content-Type:** text/plain (for upload body)
+
+**Input format (POST body for upload action):**
+```
+1,The Great Gatsby,F. Scott Fitzgerald,/Books/gatsby.epub
+2,1984,George Orwell,/Books/1984.epub
+3,Pride and Prejudice,Jane Austen,/Books/pride.epub
+```
+Format: `order,title,author,path` (one per line)
+
+**Response (upload success):**
+```json
+{"success": true, "path": "/.lists/MyReadingList.bin"}
+```
+
+**Response (delete success):**
+```json
+{"success": true}
+```
+
+**Errors:**
+- 400: Missing action or name parameter, empty name, failed to parse list data
+- 404: List not found (for delete action)
+- 500: Failed to save/delete list
+
+**Notes:**
+- Lists are stored as binary files in `/.lists/` directory
+- Uses `BookListStore::parseFromText()`, `BookListStore::saveList()`, `BookListStore::deleteList()`
+- Order field determines display order (books are sorted by order when loaded)
+- Overwrites existing list with same name on upload
+
 ## WebSocket Protocol (port 81)
 
 **Handler:** `onWebSocketEvent()` via `wsEventCallback()` trampoline
@@ -258,5 +329,6 @@ Source: `src/network/CrossPointWebServer.cpp` and `CrossPointWebServer.h`
 - `<ArduinoJson.h>` - JSON serialization
 - `<SDCardManager.h>` - SD card operations (SdMan singleton)
 - `<Epub.h>` - Epub cache management
+- `BookListStore.h` - Book list management (lists feature)
 - `BookManager.h` - Book deletion, archiving, recent books
 - `StringUtils.h` - File extension checking