feat: implement daemon model with registry and single-asset assignment (BAT-010, REQ-023/028)

Core Implementation (BAT-010):
- Add daemon registry schema and CRUD operations (req-023)
- Implement single-daemon asset assignment constraint (one asset per daemon)
- Add daemon_id field to service_token for daemon identification
- Add daemon.py CLI module for daemon management commands
- Add 20260513_0016_daemon_model.py migration for daemon tables

API Changes:
- GET /v1/assets: include daemon_id in AssetResponse
- POST /v1/assets/{asset_id}/ledger/trades: require daemon token binding
- GET /v1/user_info: include daemon metadata
- Enhanced service-token rotate to preserve daemon bindings

CLI Commands:
- pfhub daemon register --name <name> --runtime-id <runtime-id>
- pfhub daemon list
- pfhub daemon get <daemon-id>
- pfhub daemon revoke <daemon-id>

Requirements (REQ-023, REQ-028):
- REQ-023: Daemon Registry and Service Token Daemon Binding (Interface, Approved)
  * AC-1: daemon CRUD operations
  * AC-2: service token daemon binding for POST /v1/assets/{asset_id}/ledger/trades
  * AC-3: single daemon per asset (exact-one assignment model)
- REQ-028: README.md Daemon Provisioning Runbook update (Documentation, Approved)

Documentation:
- Add dcy-006 Discovery for daemon-id and single-daemon asset assignment
- Update README.md with Daemon Provisioning Runbook section
- Add BAT-010 batch documentation with planning, implementation, verification
- Update rel-006 release document (daemon model implementation)
- Update data-model.md with daemon and daemon_asset_assignment tables
- Update interface-contract.md with daemon registry APIs
- Update runtime-flows.md with daemon lifecycle flows

Breaking Changes:
- REQ-005~009, REQ-011~012 status reverted to Approved due to revised contract
  * daemon_id field addition and exact-one asset assignment requirement
  * Existing Implemented evidence invalidated by contract revision
  * BAT-001/002/008 re-verification required

Testing:
- Add test_daemon_registry.py for daemon CRUD operations
- Add test_daemon_assignment.py for single-asset assignment constraints
- Update test_auth.py, test_cli.py, test_v1.py for daemon support
- Verify daemon token binding in trade endpoint authorization

Impact:
- Database: 2 new tables (daemons, daemon_asset_assignments)
- Migration: 20260513_0016 creates daemon model schema
- CLI: 4 new daemon subcommands
- API: daemon_id propagation through v1 endpoints
- Verification: BAT-001/002/008 re-verification gates next release

app/schemas/v1.py

@@ -53,7 +53,8 @@ class BrokerItem(BaseModel):
 
 
 class UserInfoResponse(BaseModel):
-    runtime_id: str
+    runtime_id: str | None = None
+    daemon_id: str | None = None
     trading_enabled: bool
     disabled_reason: str | None = None
     brokers: list[BrokerItem] = []