feat: UX improvements — secure webhooks, locale fixes, dynamic languages, UI polish

- Remove top paginator from dashboard events, keep only bottom
- Fix test message locale: pass UI locale to email/matrix bot tests
- Convert webhook auth mode from text input to icon grid selector
- Generate secure UUID tokens for webhook URLs instead of sequential IDs
- Move Recent Payloads into per-provider expandable container (lazy-loaded)
- Make template config languages dynamic via app settings instead of hardcoded
- Change default dev port to 5175

packages/server/src/notify_bridge_server/database/models.py

@@ -33,6 +33,7 @@ class ServiceProvider(SQLModel, table=True):
     name: str
     icon: str = Field(default="")
     config: dict[str, Any] = Field(default_factory=dict, sa_column=Column(JSON))
+    webhook_token: str = Field(default_factory=lambda: uuid4().hex)
     created_at: datetime = Field(default_factory=_utcnow)