feat: preflight - prerequisites checked and tool paths recorded before wikitool runs; launcher refuses without it (#151, POSIX half)

Files changed:
- .claude/settings.json
- .gitea/workflows/ci.yml
- .gitea/workflows/nightly.yml
- .gitea/workflows/release.yml
- .gitea/workflows/tracker-live.yml
- .github/hooks/wiki-trace.json
- .gitignore
- .vibe/hooks.toml
- AGENTS.md
- CHANGES.md
- EVALS.md
- INSTALL.md
- README.md
- VERSION
- instructions/bootstrap.md
- instructions/preflight.md
- instructions/setup-instance.md
- instructions/upgrade-instance.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/cli.py
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/git_publish.py
- tools/chemenu/commands/migrate_cmd.py
- tools/chemenu/config.py
- tools/chemenu/corpus_cache.py
- tools/chemenu/prerequisites.py
- tools/chemenu/search/ripgrep.py
- tools/chemenu/tests/conftest.py
- tools/chemenu/tests/test_dist_upgrade.py
- tools/chemenu/tests/test_doctor.py
- tools/chemenu/tests/test_preflight.py
- tools/chemenu/toolpaths.py
- tools/preflight.sh
- tools/prerequisites.txt
- tools/run_wikitool.py
- tools/trace-hook
- tools/wikitool

.gitea/workflows/tracker-live.yml

@@ -51,10 +51,8 @@ jobs:
         run: |
           set -eu
           git config --global --add safe.directory "$GITHUB_WORKSPACE"
-          python3 -m venv tools/.venv
-          tools/.venv/bin/pip install --quiet --upgrade pip
-          tools/.venv/bin/pip install --quiet -r tools/requirements.txt
-          tools/.venv/bin/pip install --quiet pytest radicale
+          tools/preflight.sh
+          tools/.venv/bin/python -m pip install --quiet pytest radicale
 
       - name: Start Radicale
         run: .gitea/scripts/start-radicale.sh tools/.venv/bin/python /tmp/radicale