Settings: add dedicated DAV/Pushover tabs, fix CalDAV/CardDAV bugs

- Add admin DAV tab (rename from CalDAV/CardDAV) and Pushover tab
  - Add per-user Pushover tab (User Key only; App Token stays admin-managed)
  - Remove system-wide CalDAV/CardDAV fallback — per-user config only
  - Rewrite contacts_tool.py using httpx directly (caldav 2.x dropped AddressBook)
  - Fix CardDAV REPORT/PROPFIND using SOGo URL pattern
  - Fix CalDAV/CardDAV test endpoints (POST method, URL scheme normalization)
  - Fix Show Password button — API now returns actual credential values
  - Convert Credentials tab to generic key-value store; dedicated keys
    (CalDAV, Pushover, trusted_proxy) excluded via _DEDICATED_CRED_KEYS

server/tools/__init__.py

@@ -20,24 +20,30 @@ def build_registry(include_mock: bool = False, is_admin: bool = True):
     # Production tools — each imported lazily to avoid errors if optional
     # dependencies are missing during development
     from .brain_tool import BrainTool
+    from .browser_tool import BrowserTool
     from .caldav_tool import CalDAVTool
+    from .contacts_tool import ContactsTool
     from .email_tool import EmailTool
     from .filesystem_tool import FilesystemTool
     from .image_gen_tool import ImageGenTool
     from .pushover_tool import PushoverTool
     from .telegram_tool import TelegramTool
     from .web_tool import WebTool
+    from .webhook_tool import WebhookTool
     from .whitelist_tool import WhitelistTool
 
     if is_admin:
         from .bash_tool import BashTool
         registry.register(BashTool())
     registry.register(BrainTool())
+    registry.register(BrowserTool())
     registry.register(CalDAVTool())
+    registry.register(ContactsTool())
     registry.register(EmailTool())
     registry.register(FilesystemTool())
     registry.register(ImageGenTool())
     registry.register(WebTool())
+    registry.register(WebhookTool())
     registry.register(PushoverTool())
     registry.register(TelegramTool())
     registry.register(WhitelistTool())