fix: harden TDD/SDD/writing-plans against NameError, accidental deletes, uncommitted work

[kalarowa871-dotcom]

Summary

Hardens three superpowers skills after a real TDD session produced fragile output:

• test-driven-development: require running the FULL test suite (not just the edited file) before declaring done; flag undefined symbols in any test. Prevents NameError/ImportError slipping through when a test passes in isolation but fails in the full import tree.
• subagent-driven-development: change git clean -fdx / rm -rf from warn to NEVER without explicit human confirmation; add a Protected-files list (AGENTS.md, README, LICENSE, pyproject.toml, config/*.yaml, .env) that must not be deleted/overwritten without confirmation.
• writing-plans: make the commit step MANDATORY — a plan is not done until committed; warn that uncommitted feature work is fragile.

Verification

Re-ran a full superpowers TDD session (breakeven stop feature on a real repo): 166 passed, AGENTS.md preserved, work committed — vs. the prior session which left 3 failing tests, deleted AGENTS.md, and left work uncommitted.

Files changed

• skills/test-driven-development/SKILL.md
• skills/subagent-driven-development/SKILL.md
• skills/writing-plans/SKILL.md