fix(hooks): remove all venv auto-repair code that deleted .venv directories

BREAKING: Removes automatic venv management that was causing session failures

Changes:
- Delete scripts/venv-repair.sh (was deleting and recreating venvs)
- Remove auto-repair code from projman/hooks/startup-check.sh
- Remove venv-repair call from scripts/post-update.sh
- Remove rm -rf .venv instructions from docs/UPDATING.md and CONFIGURATION.md
- Update docs/CANONICAL-PATHS.md to remove venv-repair.sh reference

Additionally:
- Add Pre-Change Protocol to CLAUDE.md (mandatory dependency check before edits)
- Add Pre-Change Protocol enforcement to claude-config-maintainer plugin
- Add Development Context section to CLAUDE.md clarifying which plugins are
  used in this project vs only being developed
- Reorganize commands table to separate relevant vs non-relevant commands

The venv auto-repair was the root cause of repeated MCP server failures,
requiring manual setup.sh runs after every session start.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/CONFIGURATION.md

@@ -501,9 +501,8 @@ If you get 401, regenerate your token in Gitea.
 # Check venv exists
 ls /path/to/mcp-servers/gitea/.venv
 
-# Reinstall if missing
+# If missing, create venv (do NOT delete existing venvs)
 cd /path/to/mcp-servers/gitea
-rm -rf .venv
 python3 -m venv .venv
 source .venv/bin/activate
 pip install -r requirements.txt