Auto-bootstrap BSIPA when re-enabling plugins

Run bootstrap automatically on enable paths when health is bad, skip bsipa
in disable-all, and add tests for the shared bootstrap gate.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/plugin_helper/cli.py

@@ -504,6 +504,7 @@ def run(argv: list[str] | None = None) -> int:
 
         if args.command == "enable":
             instance = get_instance(inst_roots, args.instance)
+            progress = (lambda message: print(f"  {message}", flush=True))
             result = enable_disabled_plugin(
                 instance=args.instance,
                 instance_path=instance.path,
@@ -511,6 +512,7 @@ def run(argv: list[str] | None = None) -> int:
                 plugin_id=args.plugin,
                 registry=args.registry,
                 lockfile=args.lockfile,
+                progress=progress,
             )
             print(f"Enabled: {args.plugin}")
             print(f"Plan: {result['planPath']}")