Document and harden the local BYO-brain configuration surface

[jeremylongshore]

Context

The local/forker path already runs an in-process governed brain without a team API or API key, but the configuration contract was implicit. Make the BYO-brain setup discoverable and observable.

Acceptance criteria

• Document TEAMKB_BASE_PATH, TEAMKB_TENANT_ID, and optional TEAMKB_EXPORT_DIR for fork/local mode.
• Document the derived qmd index path: <base>/qmd-index/<tenant>, and distinguish it from the Markdown export tree.
• Expose mode, tenant, base path, export directory, and qmd index path in brain_status.
• Keep local mode zero-egress and tenant-scoped.
• Cover config derivation with unit tests and the built runtime with a smoke assertion.
• Keep installer/preflight output aligned with the same routing contract.

Tracking: bead iel-25a.5.3; umbrella tracking issue intent-eval-lab#287.

[jeremylongshore]

Linked bead: iel-25a.5.3 (source of truth). Use bd-sync to mirror updates.

[jeremylongshore]

bd-sync from iel-25a.5.3: BYO-brain routing implementation is pushed at commit 5e3adf8 on feat/iel-25a53-byo-brain-config. GitHub issue #55 and Plane LAB-136 created and linked. Local gates: smoke routing receipt, 83 Vitest tests, typecheck:ci, lint, and diff check pass. Draft PR pending.

[jeremylongshore]

bd-sync from iel-25a.5.3: CI failure on PR #56 diagnosed: sibling-free test job could not import @qmd-team-intent-kb/common from the new config test. Fixed in commit 4a23718 by mocking only getTeamKbBasePath at the test boundary. Hosted-safe coverage now passes locally (83 tests), plus full typecheck, lint, smoke, mode dispatch, anchors, and diff checks; pushed for CI rerun.

[jeremylongshore]

bd-sync from iel-25a.5.3: PR #56 rerun is fully green after 4a23718: Review, Adversarial review, Anchor conformance, Full-chain smoke, and Lint/typecheck/unit tests all pass. Bead remains in progress pending PR merge.

[jeremylongshore]

bd-sync from iel-25a.5.3: 2026-08-09 gate reconciliation: claim was 7 days stale with no activity — un-claiming to open per the phase-completion gate backlog-honesty pass (WIP must mean actively-worked-now). Re-claim when work actually resumes.