fix(pstack): drop agent-routing language from slash-only skill descriptions

[rufushsu9987]

Summary

Fixes #367.

Several pstack skills set disable-model-invocation: true (slash-only) but still use agent-selection language in description — especially tdd's "Use only when the user...". That guidance only makes sense for model auto-invocation, and it still lands in context when the skill is slash-invoked.

Changes

• tdd — describe the TDD workflow + /tdd triggers; drop "Use only when the user..."
• typescript-best-practices — drop "Use when reading or editing any .ts..." auto-apply tone; keep paths + slash trigger
• make-bot-ui — capability summary + /make-bot-ui instead of "Use when building..."
• reflect — "Use for /reflect" instead of "Use when the user says reflect"
• unslop — left unchanged (open fix(pstack): allow model invocation for unslop (0.15.3) #379 removes the flag there because the description says "Must always apply")
• Version 0.15.2 → 0.15.4 (avoids colliding with fix(pstack): allow model invocation for unslop (0.15.3) #379's 0.15.3)

Test plan

• Confirmed no open PR already targeting pstack: disable-model-invocation skills still have "Use only when user ..." agent instructions #367
• Frontmatter still includes disable-model-invocation: true on the four edited skills
• node scripts/validate-plugins.mjs → All plugins validated successfully
• git diff --check clean
• CI on this PR

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Note

Low Risk
Metadata-only skill description and version bump; no runtime, auth, or data-handling logic.

Overview
Rewrites frontmatter description fields on four slash-only pstack skills (disable-model-invocation: true) so they describe what the skill does and when to use /tdd, /reflect, /make-bot-ui, and /typescript-best-practices, instead of “use when the user…” language meant for model auto-routing.

tdd, typescript-best-practices, make-bot-ui, and reflect get capability-focused copy; typescript-best-practices still relies on paths for file scoping. Bumps pstack plugin version 0.15.2 → 0.15.4 (skipping 0.15.3 per related work).

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