Overview shows stale preserved worktrees as active builders

[waleedkadous]

Bug

The overview/work tab shows builders from preserved worktrees that were already cleaned up from state.db. This causes duplicate builder rows for the same issue.

Evidence

In marketmaker workspace, issue #12 shows two builder rows:

• spir-12-email-signup-interests — spawned Feb 19, cleaned up, worktree preserved
• spir-12-email-signup-with-interest-seg — spawned Feb 21, active

Only the second is in state.db. The first appears because the overview scans .builders/ on the filesystem and discovers porch project state in the preserved worktree.

Expected

Only active builders (registered in state.db) should appear in the overview. Preserved worktrees from cleaned-up builders should not be shown as active.

Root Cause

The overview endpoint discovers builders by scanning the .builders/ directory for porch project state files, in addition to (or instead of) reading from state.db. Preserved worktrees still contain codev/projects/<id>/status.yaml which gets picked up as an active project.