docs(fleet): consolidate north-star doctrine — budget governance + control plane + identity (#620-adjacent)

Folds Mos's two consolidated drafts (budgeting/200k/delegation + control-plane/
central-register) into docs/fleet/north-star.md as ONE conflict-free PR per the
merge-map. Doctrine only — no implementation.

- Stack table: +Central register (Postgres fleet schema) + Budget/spend governance
  rows; PoC-socket-hygiene note.
- New '## Budget & token governance': even-spread pacing (Jason override), hard-cap
  downgrade→queue→refuse ladder, multi-sub auto-routing, historical spend learning,
  #558 budget CLI UX; + TTY OPS INVARIANT note.
- New '## Control plane & central register': Postgres fleet schema, gateway-API-only
  access, dispatcher = @mosaicstack/forge pipeline engine + thin forge-exec adapter
  (NOT a new daemon), register backs forge, 'board' role = forge BOD.
- Phased roadmap 4/5 annotated; Decisions of record (2026-06-22) extended (200k cap,
  worker bound #8, delegation discipline, budget governance, spend mandate, unified
  identity = Fleet, role-based session naming) + control-plane subgroup.
- Future enhancements: Matrix-on-local-homeserver future transport (F4) + tmux
  attack-surface hardening. Assumptions extended.

Tracked separately / out of scope: #622 (spend template std), #623 (telemetry
product), #625 (tenant_id schema), #628 (forge-exec adapter).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EsgTQzV5YUGk1JtCLP4B83

docs/TASKS.md

@@ -78,3 +78,7 @@ Active workstream is **W1 — Federation v1**. Workers should:
 ## Fleet stand-up fixes — model_hint→--model + socket-default trap (#626) — feat/fleet-standup-fixes
 
 - Status: implemented + tested. FIX1 model_hint→MOSAIC_AGENT_MODEL→--model. FIX2 absent socket = default tmux socket (no -L) across parse/spawn/systemd-unit/observe (socketArgs helper, bare-empty shellEnvValue, conditional -L). 158 fleet tests green; shipped presets unaffected (explicit socket_name). Detail: scratchpads/fleet-standup-fixes.md.
+
+## north-star doctrine consolidation — doc PR — feat/north-star-doctrine
+
+- Status: applied Mos's consolidated merge-map to docs/fleet/north-star.md (budget governance + control plane/central register + 200k cap + delegation + unified-identity Fleet + role-based naming + tmux security + drift re-captures). Doctrine only; #622/#623/#625/#628 out-of-scope. Conflict checklist green. Detail: scratchpads/north-star-doctrine.md.