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

EVALS.md

@@ -128,7 +128,8 @@ Verified against vendor documentation on 2026-08-23.
 
 ### Claude Code
 
-`.claude/settings.json` wires `UserPromptSubmit` to `tools/trace_ingest.py`. That is what makes
+`.claude/settings.json` wires `UserPromptSubmit` to `tools/trace_ingest.py`, through
+`tools/trace-hook` like every hook here (see the load-bearing details under Copilot CLI). That is what makes
 `clearance-ended-the-turn` scorable here: without a `prompt.submitted` event there is no turn
 boundary to place an exit-42 call and its `--confirm` on either side of, and the rule reports
 "cannot say" instead of a verdict.
@@ -157,8 +158,17 @@ own decision-document schema verified against a live CLI first (this repo has no
 unverified, per the same rule that governed the Vibe adapter: an adapter that cannot be verified
 is not written.
 
-Two details in that file are load-bearing:
+Three details in that file are load-bearing, and the first holds for all three hook
+configurations:
 
+- **The interpreter is the venv's, never the script's shebang.** Each `bash` command is
+  `./tools/trace-hook ...`, which runs `trace_ingest.py` with `tools/.venv`'s Python in either
+  venv layout; each `powershell` command names `tools\.venv\Scripts\python.exe` directly. A
+  hook command is a fixed string and cannot read `.wikitool-tools.json`, but the venv is
+  created from the recorded interpreter at a fixed place, so it stands in for it. The shebang
+  (`python3`) was the Microsoft Store alias in Git Bash on Windows, which made every hook there
+  a silent no-op. Before the preflight has created the venv, `trace-hook` records nothing and
+  exits 0.
 - **Every command ends in `|| true`.** `preToolUse` hooks are *fail-closed*: a non-zero exit
   denies the tool call. Without the guard, a missing interpreter would turn the observer into
   a blocker that refuses every tool call in the session. (Timeouts are fail-open, so the