fix: remove console.log statements, use console.debug where needed

Per Obsidian plugin submission requirements, only console.warn,
console.error, and console.debug are allowed.

Changes:
- Removed console.log from main.ts (API key generation and migration)
- Removed console.log from mcp-server.ts (server start/stop messages)
- Replaced console.log with console.debug in notifications.ts
- Updated tests to expect console.debug instead of console.log

All functionality is preserved - server status is still shown via
Notice and status bar, and tool calls are still logged when enabled.

src/ui/notifications.ts

@@ -93,7 +93,7 @@ export class NotificationManager {
 
 		// Log to console if enabled
 		if (this.settings.logToConsole) {
-			console.log(`[MCP] Tool call: ${toolName}`, args);
+			console.debug(`[MCP] Tool call: ${toolName}`, args);
 		}
 	}