Inbound sync: issue updates across Linear, Jira, GitLab, Bitbucket, and Azure DevOps

Overnight ship for teams that keep feedback cards linked to tracker issues.

What changed

• Linear and Jira: issue update webhooks refresh title/body on linked Hollahoop posts (create still opens a new card).
• GitLab: Issue and Merge Request update hooks sync the same way.
• Bitbucket: issue:updated / pullrequest:updated refresh linked posts (PR updates also create when not linked yet).
• Azure DevOps: workitem.updated / git.pullrequest.updated refresh linked posts (create when missing).
• Generic git webhook: optional action: "update" with the same upsert behavior.

Also in this drop

• Public status page and leaderboard chrome localized across en/es/de/fr/pt/ja/ar.
• Docs updated in docs/GIT_CI.md and docs/BACKLOG.md.

No schema migrations required for this batch.