Plugin self-update via Gitea webhook or cron

[jordanpartridge]

Problem

Plugin changes (like the timestamp whisper fix) require manual git pull on each machine.

Solution

Either:

1. Lightweight cron that runs git -C ~/.claude/plugins/cache/conduit-ui-marketplace/know/1.0.0 pull hourly
2. Gitea webhook receiver that triggers pull on push events (Tailscale-only)

Acceptance Criteria

• Plugin updates propagate to all machines automatically
• No public endpoints required (Tailscale mesh only)
• Fallback to hourly cron if webhook unavailable

Part of v1.1.0 release.