feat(obd_ai): add foundation layer and approved command catalog

[virtuscyber]

Refs #1

This opens the foundation lane for the LLM-safe OBD diagnostics stack.

Includes:

• OBDAISession foundation
• approved command catalog and safety filtering
• initial package surface for follow-on lanes

Stack order: #1 -> #2 -> #3 -> #4 -> #5

[augmentcode]

🤖 Augment PR Summary

Summary: This PR introduces a new obd_ai foundation layer to provide LLM-safe, read-only access patterns on top of the existing obd library.

Changes:

• Added the obd_ai package surface and exports (obd_ai/__init__.py)
• Implemented an immutable ApprovedCommandCatalog that maps curated public keys to concrete obd.commands.* instances (obd_ai/catalog.py)
• Defined an MVP read-only approved command set (RPM, speed, temps, DTC reads, VIN, etc.) and a default catalog singleton
• Added OBDAISession as a constrained wrapper around an obd.OBD connection, exposing only catalog-approved queries (obd_ai/session.py)
• Added OBDAISessionManager to create/wrap sessions and support dependency injection via an obd_factory for testing
• Added unit tests covering catalog mapping/immutability and session delegation/safety checks (tests/test_obd_ai_catalog.py, tests/test_obd_ai_session.py)

Technical Notes: The catalog is enforced via key-based lookups and uses MappingProxyType + frozen dataclasses to keep the approved surface read-only.

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[augmentcode]

Review completed. 1 suggestion posted.

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[augmentcode]

tests/test_obd_ai_catalog.py:23 — "CLEAR_DTC" not in catalog is checking membership by approved key, but ApprovedCommandCatalog.__contains__ only looks at approved keys (e.g., clear_trouble_codes), not OBD command names. As written, this assertion doesn’t actually validate that the write command is excluded and may give a false sense of safety coverage.

Severity: low

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