chore: bump version and changelog (v0.15.2.1)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,17 @@
 # Changelog
 
+## [0.15.2.1] - 2026-04-02 — Setup Runs Migrations
+
+`git pull && ./setup` now applies version migrations automatically. Previously, migrations only ran during `/gstack-upgrade`, so users who updated via git pull never got state fixes (like the skill directory restructure from v0.15.1.0). Now `./setup` tracks the last version it ran at and applies any pending migrations on every run.
+
+### Fixed
+
+- **Setup runs pending migrations.** `./setup` now checks `~/.gstack/.last-setup-version` and runs any migration scripts newer than that version. No more broken skill directories after `git pull`.
+- **Space-safe migration loop.** Uses `while read` instead of `for` loop to handle paths with spaces correctly.
+- **Fresh installs skip migrations.** New installs write the version marker without running historical migrations that don't apply to them.
+- **Future migration guard.** Migrations for versions newer than the current VERSION are skipped, preventing premature execution from development branches.
+- **Missing VERSION guard.** If the VERSION file is absent, the version marker isn't written, preventing permanent migration poisoning.
+
 ## [0.15.2.0] - 2026-04-02 — Voice-Friendly Skill Triggers
 
 Say "run a security check" instead of remembering `/cso`. Skills now have voice-friendly trigger phrases that work with AquaVoice, Whisper, and other speech-to-text tools. No more fighting with acronyms that get transcribed wrong ("CSO" -> "CEO" -> wrong skill).

VERSION

@@ -1 +1 @@
-0.15.2.0
+0.15.2.1