Initialize repository timestamps on first add to prevent message flooding

[Copilot]

When adding a repository for the first time, the plugin floods the chat with all historical commits, issues, PRs, and releases because last_processed timestamps are missing. The notification logic compares item timestamps against None, treating everything as new.

Changes

• Added initialize_repo_timestamps() in repo_activity_new.py

  • Fetches latest items from all endpoints (commits, issues, PRs, releases)
  • Records timestamps in last_processed table
  • Initializes issue/PR and comment ID tracking to prevent comment flooding
  • Uses current time as fallback on fetch failures or empty repositories
  • Skips initialization if timestamps already exist

• Modified add_repo() command in commands.py

  • Calls initialize_repo_timestamps() after validating and adding repository
  • Ensures only items created after repository addition trigger notifications

Result

# Before: Adding repo triggers notifications for all 100+ historical items
await add_repo(bot, event, "/repo.add owner/repo")
# → Floods chat with all historical activity

# After: Only new items created post-addition trigger notifications  
await add_repo(bot, event, "/repo.add owner/repo")
# → Silent initialization, then tracks only new activity

Database structure:

• last_processed table: stores latest timestamp per repo/data_type
• issues/prs tables: tracks latest issue/PR ID (id=0) and latest comment ID (id=issue_id)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>第一次添加仓库时会推送大量消息</issue_title>
<issue_description>第一次添加仓库时插件会推送大量历史的提交/issue等信息。希望在没有历史仓库信息的时候能够静默查询，防止刷屏。</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes 第一次添加仓库时会推送大量消息 #27

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.