T8/P1: documentation + factoring guards (Sphinx, MCP manifest, splittability)

[mzargham]

Owner-added P1 scope (2026-08-02 review) on branch feat/t8-concept-definition-app. Discharges N5 (the app definition is a versioned, reviewed artifact).

Traceability:

• Generated MCP tool-manifest doc docs/services/mcp-manifest.md, drift-checked → tests/unit/test_docs_drift.py
• Hand-written per-surface docs: docs/services/mcp-server.md (MCP endpoint), docs/services/rest-api.md (OpenAPI/Swagger surface)
• Splittability contract docs/architecture/factoring.md + AST import-direction guards → tests/unit/test_factoring.py
• Sphinx wiring: docs/api.md (cds.mcp/cds.service autodoc), docs/index.md toctree
• Spec amendment: §7 tree + service extra + cds-api script; §8.1 transport-independence sentence

Commits reference this issue with Refs: footers. Closes only when feat/t8-concept-definition-app merges to main.

[mzargham]

P1 COMPLETE for documentation + factoring (37ac4e6; spec amendments 6ef2325, 89e0124). Per-service pages (mcp-server, facilitator, conformance-oracle, model-store) + generated mcp-manifest.md (drift-checked); docs/architecture/factoring.md with the enforced import DAG (tests/unit/test_factoring.py — AST module-level guards); Sphinx builds with contracts/mcp/facilitator/oracle autodoc + Services & architecture toctree.