feat(jobs/runners): worktree prune two-phase + workspace prune queries/repo methods

internal/workspace/queries/worktrees.sql

@@ -49,3 +49,35 @@ RETURNING *;
 
 -- name: DeleteWorktree :exec
 DELETE FROM workspace_worktrees WHERE id = $1;
+
+-- name: ListWorktreesNeedingPruneWarning :many
+SELECT * FROM workspace_worktrees
+ WHERE status = 'idle'
+   AND prune_warning_at IS NULL
+   AND last_used_at < $1
+ ORDER BY last_used_at ASC;
+
+-- name: ListWorktreesNeedingPrune :many
+SELECT * FROM workspace_worktrees
+ WHERE status = 'idle'
+   AND last_used_at < $1
+ ORDER BY last_used_at ASC;
+
+-- name: MarkPruneWarning :exec
+UPDATE workspace_worktrees
+   SET prune_warning_at = now()
+ WHERE id = $1 AND prune_warning_at IS NULL;
+
+-- name: TryStartPrune :one
+UPDATE workspace_worktrees
+   SET status = 'pruning'
+ WHERE id = $1 AND status = 'idle'
+RETURNING *;
+
+-- name: FinishPruneSuccess :exec
+DELETE FROM workspace_worktrees WHERE id = $1;
+
+-- name: FinishPruneRollback :exec
+UPDATE workspace_worktrees
+   SET status = 'idle'
+ WHERE id = $1 AND status = 'pruning';