Add Claude Code, OpenCode, and Grok observation #2

Parent: toolboxmd/model-router#3

Outcome

The same CLI and event contract observe all four requested harnesses on this Mac.

Blockers

Task 1's reviewed contract and exact candidate.

Acceptance criteria

• Three native adapters retain usage, tools, skill/read evidence, compaction, and lifecycle data at each source's actual granularity.
• Preserve model/effort evidence and source-specific reasoning/cache semantics. Do not invent per-response counters from aggregate-only sources.
• Publish a capability matrix by installed harness version, separating observed, unreported, and unsupported event families.
• Fill necessary recording gaps with bounded passive hooks where supported. Verify their actual delivery and expose capture failures.
• Claude shared-session ancestry, OpenCode parent-message links, and Grok merged-turn/synthetic-message cases behave according to the parent spec.

Non-goals

New routing choices, credential changes, broad parser forks, global hook installation, and Rocky.

Required proof

Sanitized native fixtures for each harness, replay/idempotency checks, separate ccusage token reconciliation, and real verification of each hook used. Existing four-agent evidence supplies fixtures; do not rerun those agents just to manufacture usage.

Objective contribution

Make ordinary work comparable across the user's actual harnesses.