feat(cli): sol skills install/uninstall/list replaces npx and make skills loop
- New think/skills_cli.py with user-mode (copy bundles into ~/.{claude,codex,gemini}/skills) and project-mode (symlink talent/ + apps/*/talent into <DIR>/.{claude,agents}/skills) flows.
- Registered skills in think/sol_cli.py (Specialized tools group).
- Makefile: make skills is now a one-line wrapper around sol skills install --project; dropped skills from direct prereqs of install and install-service (.installed recursion handles it); replaced npx skills add/remove with sol skills install/uninstall; deleted unused SKILL_DIRS.
- Project-mode preserves stale-symlink cleanup, dedupe-by-name error, and relative-symlink target shape from the old shell loop.
- Tests: tests/test_skills_cli.py covers user/project modes, conflict matrix, agent skip semantics, gemini conditional, dedupe, stale cleanup, CLI surface, and source-resolution.
- tests/test_journal_skill.py:test_make_skills_idempotent rewritten to drive install_project directly (no temp .venv).
- Docs: docs/SOLCLI.md and docs/project-structure.md updated to point at sol skills install --project with make skills as wrapper.