feat: enable metrics

[Gasoid]

No description provided.

[Copilot]

Pull Request Overview

This PR adds Prometheus metrics support to the merge bot application, enabling monitoring of bot commands and execution times. The changes include metrics collection for command success/failure rates and update duration tracking.

Key changes:

• Created comprehensive metrics package with Prometheus counters and histograms
• Integrated metrics collection into the bot's event handling system
• Updated Go version from 1.24.1 to 1.25.1 across build configurations

Reviewed Changes

Copilot reviewed 6 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
metrics/metrics.go	Core metrics implementation with Prometheus counters, histograms, and HTTP server
metrics/metrics_test.go	Comprehensive test suite for metrics functionality
bot.go	Integration of metrics wrapper into event handling
go.mod	Updated dependencies to include Prometheus client libraries and Go 1.25.1
Dockerfile	Updated base image to Go 1.25.1
.github/workflows/ci.yml	Updated CI workflow to use Go 1.25 and latest action versions

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