feat(metrics): add MCP client activity metrics endpoint and service

- Implemented a new Fastify route for retrieving MCP client activity metrics, including request counts, tool calls, and active clients over specified time ranges and intervals.
- Created McpClientActivityMetricsService to handle the logic for querying and aggregating metrics data from the database.
- Introduced TimeSeriesMetricsService as a base class for shared time-series metric functionalities, including time range parsing, bucket generation, and summary calculations.
- Defined schemas for request query parameters and response formats to ensure proper validation and documentation.
- Enhanced error handling and logging for better traceability of issues during metric retrieval.

Author: Lasim

services/backend/drizzle/migrations_sqlite/0008_clever_mockingbird.sql

@@ -0,0 +1,21 @@
+CREATE TABLE `mcpClientActivityMetrics` (
+	`id` text PRIMARY KEY NOT NULL,
+	`user_id` text NOT NULL,
+	`team_id` text NOT NULL,
+	`satellite_id` text NOT NULL,
+	`auth_identifier` text NOT NULL,
+	`bucket_timestamp` integer NOT NULL,
+	`bucket_interval` text CHECK(`bucket_interval` IN ('15m', '1h')) NOT NULL,
+	`request_count` integer DEFAULT 0 NOT NULL,
+	`tool_call_count` integer DEFAULT 0 NOT NULL,
+	`active_client_count` integer DEFAULT 0 NOT NULL,
+	`created_at` integer NOT NULL,
+	FOREIGN KEY (`user_id`) REFERENCES `authUser`(`id`) ON UPDATE no action ON DELETE cascade,
+	FOREIGN KEY (`team_id`) REFERENCES `teams`(`id`) ON UPDATE no action ON DELETE cascade,
+	FOREIGN KEY (`satellite_id`) REFERENCES `satellites`(`id`) ON UPDATE no action ON DELETE cascade
+);
+--> statement-breakpoint
+CREATE INDEX `mcp_activity_metrics_lookup_idx` ON `mcpClientActivityMetrics` (`user_id`,`team_id`,`bucket_timestamp`,`bucket_interval`);--> statement-breakpoint
+CREATE INDEX `mcp_activity_metrics_time_idx` ON `mcpClientActivityMetrics` (`bucket_timestamp`);--> statement-breakpoint
+CREATE INDEX `mcp_activity_metrics_satellite_idx` ON `mcpClientActivityMetrics` (`satellite_id`,`bucket_timestamp`);--> statement-breakpoint
+CREATE INDEX `mcp_activity_metrics_unique_bucket` ON `mcpClientActivityMetrics` (`user_id`,`team_id`,`satellite_id`,`auth_identifier`,`bucket_timestamp`,`bucket_interval`);