fix: pair-agent skill compliance + fix all 16 pre-existing test failures

Root cause: pair-agent was added without completing the gen-skill-docs
compliance checklist. All 16 failures traced back to this.

Fixes:
- Sync package.json version to VERSION (0.15.9.0)
- Add "(gstack)" to pair-agent description for discoverability
- Add pair-agent to Codex path exception (legitimately documents ~/.codex/)
- Add CLI_COMMANDS (status, pair-agent, tunnel) to skill parser allowlist
- Regenerate SKILL.md for all hosts (claude, codex, factory, kiro, etc.)
- Update golden file baselines for ship skill
- Fix relink tests: pass GSTACK_INSTALL_DIR to auto-relink calls so they
  use the fast mock install instead of scanning real ~/.claude/skills/gstack

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pair-agent/SKILL.md

@@ -7,7 +7,7 @@ description: |
   Hermes, Codex, Cursor, or any agent that can make HTTP requests. The remote agent
   gets its own tab with scoped access (read+write by default, admin on request).
   Use when asked to "pair agent", "connect agent", "share browser", "remote browser",
-  "let another agent use my browser", or "give browser access".
+  "let another agent use my browser", or "give browser access". (gstack)
   Voice triggers (speech-to-text aliases): "pair agent", "connect agent", "share my browser", "remote browser access".
 allowed-tools:
   - Bash

pair-agent/SKILL.md.tmpl

@@ -7,7 +7,7 @@ description: |
   Hermes, Codex, Cursor, or any agent that can make HTTP requests. The remote agent
   gets its own tab with scoped access (read+write by default, admin on request).
   Use when asked to "pair agent", "connect agent", "share browser", "remote browser",
-  "let another agent use my browser", or "give browser access".
+  "let another agent use my browser", or "give browser access". (gstack)
 voice-triggers:
   - "pair agent"
   - "connect agent"