Add Audible region config and user password change modal

Implements configurable Audible region selection in setup and admin settings, affecting all Audible API calls and triggering data refresh on change. Adds a user-facing 'Change Password' modal in the header for local users, moving password change from admin-only to all local users via a new /api/auth/change-password endpoint. Updates documentation, API routes, and context to support these features, and removes the old admin-only password change flow.

documentation/settings-pages.md

@@ -6,13 +6,39 @@ Single tabbed interface for admins to view/modify system configuration post-setu
 
 ## Sections
 
-1. **Plex** - URL, token (masked), library ID, filesystem scan trigger toggle
-2. **Audiobookshelf** - URL, API token (masked), library ID, filesystem scan trigger toggle
+1. **Plex** - URL, token (masked), library ID, Audible region, filesystem scan trigger toggle
+2. **Audiobookshelf** - URL, API token (masked), library ID, Audible region, filesystem scan trigger toggle
 3. **Prowlarr** - URL, API key (masked), indexer selection with priority, seeding time, RSS monitoring toggle
 4. **Download Client** - Type, URL, credentials (masked)
 5. **Paths** - Download + media directories
 6. **BookDate** - AI provider, API key (encrypted), model selection, library scope, custom prompt, swipe history
-7. **Account** - Local admin password change (only visible to setup admin)
+
+## Audible Region
+
+**Purpose:** Configure which Audible region to use for metadata and search to ensure accurate ASIN matching with your metadata engine.
+
+**Configuration:**
+- Key: `audible.region` (string, default: 'us')
+- Supported regions: US, Canada, UK, Australia, India
+- UI: Dropdown selector in Library tab (both Plex and Audiobookshelf settings)
+- No validation required (immediate save)
+
+**Why It Matters:**
+- Each Audible region uses different ASINs for the same audiobook
+- Users must match their RMAB region to their Plex/Audiobookshelf metadata engine region
+- Mismatched regions cause poor search results and failed metadata matching
+
+**Help Text:**
+"Select the Audible region that matches your metadata engine (Audnexus/Audible Agent) configuration in [Plex/Audiobookshelf]. This ensures accurate book matching and metadata."
+
+**Implementation:**
+- Affects all Audible API calls (base URL changes per region)
+- Affects all Audnexus API calls (region parameter added)
+- Changes apply immediately on next API call (no restart required)
+- **Automatic refresh**: Changing region automatically triggers `audible_refresh` job to fetch popular/new releases for the new region
+- **Cache management**: ConfigService cache and AudibleService initialization are cleared when region changes
+- **Smart re-initialization**: Service automatically detects region changes and re-initializes before each request
+- See: `documentation/integrations/audible.md` for technical details
 
 ## Filesystem Scan Trigger
 
@@ -72,19 +98,11 @@ Single tabbed interface for admins to view/modify system configuration post-setu
 4. **Save:** Updates user preferences immediately
 5. Accessible to all authenticated users
 
-**Account (local admin only):**
-1. Local admin can change password
-2. Requires: current password, new password (min 8 chars), confirmation
-3. No "Save Changes" button - uses dedicated "Change Password" button
-4. Form clears after successful change
-5. Only visible to users with `isSetupAdmin=true` AND `plexId` starts with `local-`
-
 **Validation state resets when:**
 - Plex: URL or token modified
 - Prowlarr: URL or API key modified (NOT indexer config)
 - Download Client: URL, username, or password modified
 - Paths: Directory paths modified
-- Account: No validation required (password change is immediate)
 
 ## API Endpoints
 
@@ -106,6 +124,11 @@ Single tabbed interface for admins to view/modify system configuration post-setu
 - Updates Prowlarr URL and API key
 - Requires prior successful test if values changed
 
+**PUT /api/admin/settings/audible**
+- Updates Audible region
+- Body: `{ region: string }` (one of: us, ca, uk, au, in)
+- No validation required
+
 **PUT /api/admin/settings/prowlarr/indexers**
 - Updates indexer configuration (enabled, priority, seeding time, RSS)
 - No test required if URL/API key unchanged
@@ -133,10 +156,6 @@ Single tabbed interface for admins to view/modify system configuration post-setu
 - GET /api/bookdate/preferences - Get user's preferences (libraryScope, customPrompt)
 - PUT /api/bookdate/preferences - Update user's preferences (all authenticated users)
 
-**Account Endpoints:**
-- POST /api/admin/settings/change-password - Change local admin password (local admin only)
-- GET /api/auth/is-local-admin - Check if current user is local admin (returns `{isLocalAdmin: boolean}`)
-
 ## Features
 
 - Password visibility toggle