Restore files missing from the patch set: agent skills, .gitignore, CI workflow

[devin-ai-integration]

Summary

Compared every file in patches 12 and 15 against this repo (mapping the original nm-ccm-migration/<pkg>/ layout onto src/<pkg>/). Everything landed except three groups, which this PR restores, adapted to the root/src layout and the anonymized naming already used here:

• .agents/skills/ (all six): assess-form-corpus, convert-xdp-form, prepare-designer-handoff, review-rulebook-change, triage-designer-errors, validate-pdf-output. AGENTS.md, README and every playbook already reference them. Paths rewritten fixtures/ -> src/fixtures/, decisions/ -> src/decisions/, etc.; NM_FIXTURE_ROOT -> CCM_FIXTURE_ROOT (matching src/tools); customer/partner names replaced as in the rest of the repo.
• .gitignore: src/fixtures/raw/* (hard rule 6 assumed this was already ignored), import_logs/composition_logs *.json, plus out/, caches, *.egg-info/, .venv/.
• .github/workflows/ccm-migration.yml: same verify job as the original (ruff check, rulebook/dictionary lint, pytest, tools.report, conditional tools.pipeline when vars.CCM_FIXTURE_ROOT is set), without the subdirectory working-directory/path filters, plus ruff format --check.
• README layout block lists all six skills instead of three.

The two knowledge/nm-*.md files from the patches exist here as knowledge/customer-*.md; not duplicated. Raw customer artifacts are not in the patches and are not added.

Verified locally: ruff check ., ruff format --check ., pytest -q (90 passed, 7 skipped without raw artifacts), rulebook/dictionary imports and tools.report all succeed.

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/060b9626e9ad430186f22f341a34278b
Open in Devin Desktop: https://partner-workshops.devinenterprise.com/desktop/session/060b9626e9ad430186f22f341a34278b?variant=devin
Requested by: @sumitshatwara

[devin-ai-integration]

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