Add GitHub webhook platform adapter

[Copilot]

Adds GitHub webhook platform support to receive and process repository events (issue created, issue comment, PR created) within AstrBot's messaging system.

Modifications / 改动点

New Platform Adapter (astrbot/core/platform/sources/github_webhook/)

• github_webhook_adapter.py: Platform adapter implementing webhook callback handling
  • Processes issues (opened), issue_comment (created), pull_request (opened) events
  • HMAC signature verification (SHA256/SHA1) with timing-safe comparison
  • Formats events as structured messages with repo, author, title, content preview
• github_webhook_event.py: Event wrapper storing GitHub event metadata

Platform Registration

• manager.py: Added github_webhook to platform loader

Security

• Optional webhook secret for request authentication
• Rejects invalid signatures with HTTP 401
• Supports both X-Hub-Signature-256 and legacy X-Hub-Signature headers

Integration

• Uses unified webhook mode via dashboard endpoint /api/platform/webhook/{uuid}
• Gracefully handles unsupported events and actions

Tests (tests/test_github_webhook.py)

• 9 test cases: initialization, event handling, signature verification, error cases
• All passing

Example webhook configuration:

{
    "type": "github_webhook",
    "enable": true,
    "id": "my_github_webhook",
    "unified_webhook_mode": true,
    "webhook_uuid": "unique-uuid-here",
    "webhook_secret": "optional-secret"  # For signature verification
}

• This is NOT a breaking change. / 这不是一个破坏性变更。

Screenshots or Test Results / 运行截图或测试结果

tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_adapter_initialization PASSED [ 11%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_ping_event PASSED [ 22%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_issue_created_event PASSED [ 33%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_issue_comment_event PASSED [ 44%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_pull_request_event PASSED [ 55%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_unsupported_event PASSED [ 66%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_issue_closed_ignored PASSED [ 77%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_signature_verification PASSED [ 88%]
tests/test_github_webhook.py::TestGitHubWebhookAdapter::test_invalid_signature PASSED [100%]

9 passed, 1 warning in 2.99s

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Checklist / 检查清单

• 😊 如果 PR 中有新加入的功能，已经通过 Issue / 邮件等方式和作者讨论过。/ If there are new features added in the PR, I have discussed it with the authors through issues/emails, etc.
• 👀 我的更改经过了良好的测试，并已在上方提供了"验证步骤"和"运行截图"。/ My changes have been well-tested, and "Verification Steps" and "Screenshots" have been provided above.
• 🤓 我确保没有引入新依赖库，或者引入了新依赖库的同时将其添加到了 requirements.txt 和 pyproject.toml 文件相应位置。/ I have ensured that no new dependencies are introduced, OR if new dependencies are introduced, they have been added to the appropriate locations in requirements.txt and pyproject.toml.
• 😮 我的更改没有引入恶意代码。/ My changes do not introduce malicious code.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• api.soulter.top
  • Triggering command: /home/REDACTED/work/AstrBot/AstrBot/.venv/bin/pytest pytest tests/ -v -k not test_main --tb=short (dns block)
• example.com
  • Triggering command: /home/REDACTED/work/AstrBot/AstrBot/.venv/bin/pytest pytest tests/ -v -k not test_main --tb=short (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

add GitHub WebHook platform. Supports event: issue created, comment, pr created.

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