feat(skills): rename shortcuts skill and auto-enable caveman/ponytail on install

Rename the portable conversation-shortcut skill from agent-shortcuts to
shortcuts and re-prefix every token to soc* (sobu, soco, socobu, socon,
sona, sote) so each token mirrors its command and never places two
consonants next to each other. make install and make project now also
register the caveman and ponytail marketplaces and enable both plugins in
the target's .claude/settings.json so their SessionStart hooks activate
every session; the merge is non-destructive, idempotent, and leaves an
unparseable settings.json untouched.

- skills/shortcuts/SKILL.md: new name and soc* token table
- tests/test_shortcuts.py: assert present, sorted, soc-prefixed, no cluster
- remove skills/agent-shortcuts and tests/test_agent_shortcuts.py
- scripts/enable-plugins.js: node JSON merge helper
- scripts/install.sh: run the helper after copying skills
- README.md: document the auto-enable behavior

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -26,6 +26,8 @@ Copy the skills into a specific project (`<repo>/.agents/skills` and `<repo>/.cl
 make project TARGET=/path/to/repo
 ```
 
+Both commands also enable the caveman and ponytail plugins in the target's `.claude/settings.json` so their modes auto-activate on session start; existing settings are preserved.
+
 Restart your agent afterwards so it loads the new skills.
 
 ## Maintenance 🔧