Git cache PVC for faster repo operations

[oldsj]

Problem

Each K8s Job currently clones the repo from scratch. This is slow, especially for:

• Implement/feedback cycles on the same task
• Multiple tasks against the same repo
• Larger repositories

Solution

Add a shared git cache PVC that persists across jobs:

/git-cache/
  github.com/
    oldsj/
      mainloop.git/      # bare repo cache
    someorg/
      their-repo.git/

Behavior

1. First request for a repo → clone bare repo to cache
2. Subsequent requests (any task) → git fetch to update, clone locally from cache
3. Different repo → clone that one too, cache grows over time

Jobs use git clone --reference /git-cache/... --dissociate for fast local clones.

Future: Project Management

Layer on top of cache:

• Track which repos mainloop knows about in DB
• Per-repo settings (default branch, CI requirements, etc)
• /add-project command to register new repos