feat: donation banner, About tab, settings UI improvements

- Dismissible donation/open-source banner after 3+ sessions (30-day snooze)
- New About tab in Settings: version, repo link, license info
- Centralize project URLs (REPO_URL, DONATE_URL) in __init__.py, served via /health
- Center settings tab bar, reduce tab padding for 6-tab fit
- External URL save button: icon button instead of full-width text button
- Remove redundant settings footer close button
- Footer "Source Code" link replaced with "About" opening settings
- i18n keys for en/ru/zh

server/src/wled_controller/api/schemas/system.py

@@ -13,7 +13,11 @@ class HealthResponse(BaseModel):
     timestamp: datetime = Field(description="Current server time")
     version: str = Field(description="Application version")
     demo_mode: bool = Field(default=False, description="Whether demo mode is active")
-    auth_required: bool = Field(default=True, description="Whether API key authentication is required")
+    auth_required: bool = Field(
+        default=True, description="Whether API key authentication is required"
+    )
+    repo_url: str = Field(default="", description="Source code repository URL")
+    donate_url: str = Field(default="", description="Donation page URL")
 
 
 class VersionResponse(BaseModel):
@@ -84,6 +88,7 @@ class RestoreResponse(BaseModel):
 
 # ─── Auto-backup schemas ──────────────────────────────────────
 
+
 class AutoBackupSettings(BaseModel):
     """Settings for automatic backup."""
 
@@ -119,6 +124,7 @@ class BackupListResponse(BaseModel):
 
 # ─── MQTT schemas ──────────────────────────────────────────────
 
+
 class MQTTSettingsResponse(BaseModel):
     """MQTT broker settings response (password is masked)."""
 
@@ -138,17 +144,22 @@ class MQTTSettingsRequest(BaseModel):
     broker_host: str = Field(description="MQTT broker hostname or IP")
     broker_port: int = Field(ge=1, le=65535, description="MQTT broker port")
     username: str = Field(default="", description="MQTT username (empty = anonymous)")
-    password: str = Field(default="", description="MQTT password (empty = keep existing if omitted)")
+    password: str = Field(
+        default="", description="MQTT password (empty = keep existing if omitted)"
+    )
     client_id: str = Field(default="ledgrab", description="MQTT client ID")
     base_topic: str = Field(default="ledgrab", description="Base topic prefix")
 
 
 # ─── External URL schema ───────────────────────────────────────
 
+
 class ExternalUrlResponse(BaseModel):
     """External URL setting response."""
 
-    external_url: str = Field(description="External base URL (e.g. https://myserver.example.com:8080). Empty = use auto-detected URL.")
+    external_url: str = Field(
+        description="External base URL (e.g. https://myserver.example.com:8080). Empty = use auto-detected URL."
+    )
 
 
 class ExternalUrlRequest(BaseModel):
@@ -159,10 +170,13 @@ class ExternalUrlRequest(BaseModel):
 
 # ─── Log level schemas ─────────────────────────────────────────
 
+
 class LogLevelResponse(BaseModel):
     """Current log level response."""
 
-    level: str = Field(description="Current effective log level name (e.g. DEBUG, INFO, WARNING, ERROR, CRITICAL)")
+    level: str = Field(
+        description="Current effective log level name (e.g. DEBUG, INFO, WARNING, ERROR, CRITICAL)"
+    )
 
 
 class LogLevelRequest(BaseModel):