feat(config): add federated tier and rename team→standalone (FED-M1-01)

Aligns mosaic.config tier vocabulary with the federation PRD:
- Adds `federated` to the tier enum (Postgres + Valkey + pgvector)
- Renames `team` → `standalone` in StorageTier / GatewayStorageTier
- Keeps `team` as a deprecated alias that warns to stderr and maps to standalone
- Adds DEFAULT_FEDERATED_CONFIG (port 5433, pgvector memory)
- Corrects DEFAULT_STANDALONE_CONFIG.memory to keyword (PRD line 247)
- Wizard interactive promptTier offers local/standalone/federated
- Wizard headless env path now hard-rejects unknown MOSAIC_STORAGE_TIER
  values with a message naming all three valid tiers
- Interactive DATABASE_URL pre-fill is tier-aware: standalone→5432, federated→5433
- 10 new unit tests for the validator + 3 new wizard headless tests

No new behavior beyond the enum and defaults — pgvector enforcement,
tier-detector, and docker-compose overlays land in FED-M1-02..04.

Refs #460

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/scratchpads/mvp-20260312.md

@@ -305,3 +305,41 @@ Issues closed: #52, #55, #57, #58, #120-#134
 | Install-ux-v2 manifest + tasks + scratchpad + iuv-m03-design                           | moved to `docs/archive/missions/install-ux-v2-20260405/` with status corrected to complete |
 
 **Next:** PR `docs/mvp-mission-manifest` → merge to `main` → next session begins W1 / FED-M1 from clean state.
+
+---
+
+## Session 16 — 2026-04-19 — claude
+
+**Mode:** Delivery (W1 / FED-M1 execution)
+**Branch:** `feat/federation-m1-tier-config`
+**Context budget:** 200K, currently ~45% used (compaction-aware)
+
+**Goal:** FED-M1-01 — extend `mosaic.config.json` schema: add `"federated"` to tier enum.
+
+**Critical reconciliation surfaced during pre-flight:**
+
+The federation PRD (`docs/federation/PRD.md` line 247) defines three tiers: `local | standalone | federated`.
+The existing code (`packages/config/src/mosaic-config.ts`, `packages/mosaic/src/types.ts`, `packages/mosaic/src/stages/gateway-config.ts`) uses `local | team`.
+
+`team` is the same conceptual tier as PRD `standalone` (Postgres + Valkey, no pgvector). Rather than carrying a confusing alias forever, FED-M1-01 will rename `team` → `standalone` and add `federated` as a third value, so all downstream federation work has a coherent vocabulary.
+
+Affected files (storage-tier semantics only — Team/workspace usages unaffected):
+
+- `packages/config/src/mosaic-config.ts` (StorageTier type, validator enum, defaults)
+- `packages/mosaic/src/types.ts` (GatewayStorageTier)
+- `packages/mosaic/src/stages/gateway-config.ts` (~10 references)
+- `packages/mosaic/src/stages/gateway-config.spec.ts` (test references)
+- Possibly `tools/e2e-install-test.sh` (referenced grep) and headless env hint string
+
+**Worker plan:**
+
+1. Spawn sonnet subagent with explicit task spec + the reconciliation context above.
+2. Worker delivers diff; orchestrator runs `pnpm typecheck && pnpm lint && pnpm format:check`.
+3. Independent `feature-dev:code-reviewer` subagent reviews diff.
+4. Second independent verification subagent (general-purpose, sonnet) verifies reviewer's claims and confirms all `'team'` storage-tier references migrated, no `Team`/workspace bleed.
+5. Open PR via tea CLI; wait for CI; queue-guard; squash merge; record actuals.
+
+**Open items:**
+
+- `MVP-T04` (sync `.mosaic/orchestrator/mission.json`) still deferred.
+- `team` tier rename touches install wizard headless env vars (`MOSAIC_STORAGE_TIER=team`); will need 0.0.x deprecation note in scratchpad if release notes are written this milestone.