feat: lint reports sections that hold only template placeholders as Unfilled Template Sections (#94)

Files changed:
- CHANGES.md
- EVALS.md
- VERSION
- instructions/wiki-lint/SKILL.md
- instructions/wiki-manage/SKILL.md
- tools/CONTRACT.md
- tools/chemenu/blocks.py
- tools/chemenu/commands/lint.py
- tools/chemenu/evals/scorecard.py
- tools/chemenu/lint_core.py
- tools/chemenu/tests/test_blocks.py
- tools/chemenu/tests/test_evals.py
- tools/chemenu/tests/test_lint.py
- tools/chemenu/tests/test_pipeline_l0.py
- types/type-spec.md

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

tools/CONTRACT.md

@@ -1132,6 +1132,7 @@ Run structural lint checks against kb/.
 - Advisory only: source pages sitting in the `unclassified` catalog slot.
 - Advisory only: Long Paths - a file under `kb/` or `raw/` whose path below the instance root is over 160 UTF-16 code units, the budget that keeps a Windows checkout without long paths working. Reported as `{path, length}`; a corpus over the budget breaks no lint run. `wikitool rename` is the fix for a page.
 - Advisory only: quote-limit overages (>2 blockquotes/page).
+- Advisory only: Unfilled Template Sections - a page with at least one `##` section whose non-blank lines are all template placeholders (content starting with `TODO`, after an optional list marker, checkbox, table cell or bold field label), reported as `{page, sections}`. Code, generated regions and footnote definitions do not count; an empty section, or one placeholder beside written lines, is no finding. Writing the section from the page's sources or retiring the page is the fix - not a mechanical one.
 - Prints only the sections that found something and always writes the full report to `reports/Lint Report <date>.md` (or `--markdown`), naming the path. `--full` prints everything; `--json` prints the findings and writes nothing.
 - Exits 0 whatever it finds unless `--fail-on-error` is passed.