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/TASKS.md

@@ -28,7 +28,7 @@ These are MVP-level checks that don't belong to any single workstream. Updated b
 | MVP-T02 | done        | Archive install-ux-v2 mission state to `docs/archive/missions/install-ux-v2-20260405/`                   | IUV-M03 retroactively closed (shipped via PR #446 + releases 0.0.27→0.0.29)             |
 | MVP-T03 | done        | Land federation v1 planning artifacts on `main`                                                          | PR #468 merged 2026-04-19 (commit `66512550`)                                           |
 | MVP-T04 | not-started | Sync `.mosaic/orchestrator/mission.json` MVP slot with this manifest (milestone enumeration, etc.)       | Coord state file; consider whether to repopulate via `mosaic coord` or accept hand-edit |
-| MVP-T05 | not-started | Kick off W1 / FED-M1 — federated tier infrastructure                                                     | First execution task in MVP                                                             |
+| MVP-T05 | in-progress | Kick off W1 / FED-M1 — federated tier infrastructure                                                     | Session 16 (2026-04-19): FED-M1-01 in-progress on `feat/federation-m1-tier-config`      |
 | MVP-T06 | not-started | Declare additional workstreams (web dashboard, TUI/CLI parity, remote control, etc.) as scope solidifies | Track each new workstream by adding a row to the Workstream Rollup                      |
 
 ## Pointer to Active Workstream