#379 fix(pstack): allow model invocation for unslop (0.15.3)

Why

The unslop description says "Must always apply." The frontmatter said the opposite. disable-model-invocation: true limited the skill to an explicit /unslop call, so the agent could not select it on its own when it wrote prose. PR #300 added the flag to five skills at once. This PR removes it from unslop only.

Scope

• pstack/skills/unslop/SKILL.md. Remove the disable-model-invocation: true line. name and description are unchanged. The body is unchanged.
• pstack/.cursor-plugin/plugin.json. Version 0.15.2 to 0.15.3.
• Nothing else. The flag on every other pstack skill stays. No README line claims unslop is slash-only, so the README is unchanged.

Blast Radius

Two lines. After the plugin updates, the agent can auto-select unslop from its description. /unslop still works as before. Skills that cite unslop by name (poteto-mode, technical-writing, teach, recall, blast-radius, show-me-your-work, automate-me) are not affected.

Verification

• rg -n 'disable-model-invocation' pstack/skills/unslop/SKILL.md returns nothing.
• plugin.json reports 0.15.3.
• node scripts/validate-plugins.mjs prints "All plugins validated successfully." with ajv and ajv-formats installed as the CI workflow installs them.
• git diff --stat origin/main...HEAD is two files, one insertion, two deletions.