Add tiered access control for supply-chain risk workflows

[falltwo]

Summary

• Add server-enforced L1/L2/L3 demo accounts, organization entitlements, capabilities, scoped navigation, and scoped supply-chain/ERP views.
• Harden approval execution across the Web, LINE, scheduler, Agent Dashboard, and ERP exchange paths with live actor checks, canonical requesters, self-approval prevention, CAS claims, and execution receipts.
• Default demo-account seeding to off, document safe demo setup, and add reconciliation guidance for interrupted generic approvals.

Validation

• 284 passed in 44.19s
• Python compileall: passed
• git diff --check: passed
• Gitleaks v8.30.1: 0 findings in repository history and working tree
• Independent code review: APPROVE
• Independent security/governance review: ACCEPT

Scope and known limitations

• This is a single-organization local demo only; it is not production multi-tenant IAM, SSO, or an identity-provider integration.
• Fixed demo account names can collide with accounts in a previously initialized database. Seed them only in a clean, isolated demo database with explicit ERP_DEMO_MODE=true. Returning the flag to false does not delete accounts that were already seeded.
• Generic legacy tool execution and its receipt are not yet atomic in the same database transaction. A crash after the tool effect but before receipt persistence can leave an approval in executing; the system intentionally does not auto-retry it. Follow the generic approval reconciliation runbook.
• Pre-existing local filesystem path strings found in already-public main history are tracked separately in Track historical local-path strings in pre-existing main commits #6. This pull request cleans the current tip and does not rewrite repository history.

Access model demonstrated

• L1 / risk viewer: monitoring and alerts only.
• L2 / supply planner: L1 plus analysis, What-if simulation, and proposals; no direct ERP policy mutation.
• L3 / procurement approver: L1 plus scoped proposal evidence, approval, export, and reconciliation; requesters cannot approve their own actions.