v1.33.2.0 fix: setup guards against Conductor worktree pollution of global install (#1446)

* fix(setup): skip Claude skill registration when run from a worktree of the global install

Add a guard before `ln -snf "$SOURCE_GSTACK_DIR" "$HOME/.claude/skills/gstack"`
that detects whether the target already exists as a separate real directory.
On macOS/BSD, `ln -snf SRC DST` does not replace a real DST — it creates
DST/$(basename SRC) → SRC inside it. Running ./setup from each Conductor
worktree of the gstack repo was leaking per-worktree child symlinks into the
global install, which Claude Code then picked up as separate top-level skills.

The guard uses `cd ... && pwd -P` to resolve the existing real dir and compare
against the source (mirroring setup's own `SOURCE_GSTACK_DIR` resolution).
When they differ, prints a four-line remediation hint naming both paths and
exits the Claude registration branch cleanly. Binaries still build locally.

The four other code paths through this branch are unchanged: fresh install,
retarget an existing symlink, self-rerun where the existing dir resolves to
the same source, and --local installs.

Includes 8 tests covering static guard placement, `pwd -P` resolution, the
remediation message, a behavioral reproduction of the BSD `ln -snf` child-
symlink bug, and every branch of the guard (skip on real-dir-elsewhere, allow
on fresh, allow on existing symlink, allow on self-rerun).

* chore: bump version and changelog (v1.33.2.0)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.33.1.0",
+  "version": "1.33.2.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",