feat: export guidelines - the guideline pages as a generated GUIDELINES.md, pushed into the captured repositories behind the Guideline Push Gate (#179)

Files changed:
- AGENTS.md
- CHANGES.md
- README.md
- VERSION
- docs/why-gates-are-code.md
- instructions/gates.md
- instructions/kb-profiles.md
- kb/CONTRACT.md
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/cli.py
- tools/chemenu/cli_contract.py
- tools/chemenu/commands/export_cmd.py
- tools/chemenu/commands/page_ops.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/commands/search.py
- tools/chemenu/guideline_export.py
- tools/chemenu/kb_scan.py
- tools/chemenu/repo_capture.py
- tools/chemenu/search/filters.py
- tools/chemenu/tests/test_cli.py
- tools/chemenu/tests/test_export_guidelines.py

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

instructions/kb-profiles.md

@@ -55,7 +55,7 @@ is not a profile.
 
    | File | Holds | Profiles below |
    |---|---|---|
-   | `kb/CONVENTIONS.md` | Language, section headings, naming forms, tone, relationship labels, the hedging rule - once per instance | [Language profiles](#language-profiles) |
+   | `kb/CONVENTIONS.md` | Language, section headings, naming forms, tone, relationship labels, the hedging rule, which pages leave as guidelines - once per instance | [Language profiles](#language-profiles) |
    | `kb/<name>/COLLECTION.md` | What one collection holds, its quality goal, its local linking and naming rules | [Collection profiles](#collection-profiles) |
 
 2. **Copy the entry's text into the file**, then edit it until it is true of this instance.