[codex] add workflow preset visual item matrix contract

[bigsmartben]

Description

Adds the workflow preset Visual Item Matrix contract to the integrated spec-kit repository and keeps the integration checks aligned with the bundled preset manifest.

This updates:

• presets/workflow-preset schema, docs, commands, templates, validator, and contract tests
• presets/catalog.json bundled template count
• .github/workflows/community-smoke.yml and .github/workflows/workflow-preset-integration.yml so Actions verify the new bundled schema file
• tests/test_presets.py assertions for the workflow verification lists

Testing

• Tested locally with uv run specify --help
• Ran existing tests with uv sync && uv run pytest
• Tested with a sample project (if applicable)

Additional validation run:

• uv sync --extra test - OK
• uvx ruff check src/ - OK
• uv run pytest tests/integrations/test_cli.py -k "community_extensions_and_workflow_preset_auto_installed or workflow_preset_registers" -v - OK, 2 passed
• uv run pytest tests/test_presets.py -k "workflow_preset or bundled_preset" -v - OK, 9 passed
• From presets/workflow-preset: python -m unittest tests/test_preset_contract.py - OK, 133 tests, 2 skipped
• git diff --check - OK
• python -c "import json; json.load(open('presets/catalog.json', encoding='utf-8')); print('Valid JSON')" - OK

Full local uv run pytest was attempted on Windows: 3771 passed, 165 skipped, 10 failed. The failures were local environment issues unrelated to this change: symlink creation blocked by WinError 1314 and two default-GBK fixture reads. CI should exercise the workflow-defined Linux/Windows matrix.

AI Disclosure

• I did not use AI assistance for this contribution
• I did use AI assistance (describe below)

Used Codex to inspect the integrated repository workflows, update the PR branch, run local validation, and prepare this PR.