docs: document Home seating and group stores

[dirvine]

POST /home/seat and POST /groups/:id/stores are registered API/CLI surfaces, but neither had a normalized route entry in the API reference. This documents their actual authentication classes, request and response schemas, status/error outcomes, idempotency, and acceptance limits from the handlers and middleware.

• Home seating requires the durable owner token and mints an addressed invite; seated: false makes clear that success does not prove delivery, redemption, or membership.
• Group-store creation accepts owner bearer/session authentication, while rider tokens are denied by middleware. It distinguishes a new store missing its secret (409) from an existing handle returning metadata (200, possibly epoch: 0) and states that metadata does not prove operational readiness.

Source checks used base b2d3166fea3941ebc3f86a9995433687d08246f4, including the router/API registry, authentication middleware, both handlers, CLI wiring, and the ADR-0060 owner-driven adoption subsection. git diff --check passed, and the corrected candidate received an independent CLEAN review. This is documentation-only source conformance; it does not claim full API authentication coverage or end-to-end runtime acceptance, and it does not change ADR status.

Greptile Summary

This documentation-only PR adds normalized API-reference entries for Home seating and group-encrypted store creation.

• Documents the durable-owner authentication, addressed-invite behavior, response contract, conflicts, and acceptance limits for POST /home/seat.
• Documents owner/session authentication, rider rejection, group-security prerequisites, deterministic identity, idempotency, and readiness caveats for POST /groups/:id/stores.
• Aligns both routes with their registered CLI surfaces and current handler behavior.

Confidence Score: 5/5

The documentation changes appear safe to merge and accurately describe the current API, authentication, CLI, and handler contracts.

No actionable discrepancies were found between the added reference material and the registered routes, middleware, handlers, persistence behavior, or CLI wiring.

Important Files Changed

Filename	Overview
docs/api-reference.md	Adds source-conformant route-table entries and detailed contracts for Home seating and group-encrypted store creation.

_{Reviews (1): Last reviewed commit: "Merge branch 'main' into codex/api-home-..." | Re-trigger Greptile}

Context used (3)

• Knowledge Base — Server APIs and live streams
• Knowledge Base — Group lifecycle and membership
• Knowledge Base — Command-line and daemon entrypoints