feat(projection): seal global todo and risk reads

[Duang777]

Goal

Replace the stalled #5598 slice on current main. global-todos and global-risks now disclose source freshness and global coverage through the existing TypeScript-owned projection envelope. Corrupt host-poll receipts can no longer produce a fresh, complete result.

This PR preserves #5598's design and credit. It does not modify the original author's branch.

Changes

• Seal global_todos and global_risks with projection.envelope.seal, including Markdown readback.
• Classify an absent opt-in host-poll receipt as normal and an invalid existing receipt as unreadable.
• Validate the complete v0 receipt shape and its goal identity at the read boundary.
• Keep public-safe error responses available when the TypeScript runtime cannot seal an error envelope.
• Update the RFC checkpoint and projection-envelope carrier reference.

projection.envelope.seal remains the only freshness and completeness owner. The Python code only gathers source facts. The receipt reader reuses the existing envelope read-status vocabulary and does not add a shared state contract.

Verification

• Failing before: test_global_risks_discloses_unreadable_host_poll_receipts_and_recovers reached KeyError: 'projection_envelope' on the old implementation.
• 108 passed: projection-envelope, host-poll receipt, global-risk, and global-todo tests. This includes the real CLI global-membership failure and recovery path.
• 8 passed: TypeScript projection-envelope kernel tests.
• Ruff, git diff --check, Python compile checks, and the semantic vocabulary advisory passed.
• The live project-registry I/O census is current at 314 sites. Current main computes this report and does not track the retired generated manifest.
• Premerge direct checks, the public-boundary check, and 16 selected smokes passed.

Known baseline failures

The premerge gate still reports two risk-profile failures:

• examples/auto-research-quota-pause-smoke.py
• examples/auto-research-state-aware-wake-smoke.py

Both fail at goal-storage bootstrap with the same EffectRuntimeInternalError on unchanged latest main. The maintainability smoke is also reported as an inherited advisory and does not name a changed file.

Delivery boundary

The affected entry points are loopx global-todos and loopx global-risks, in JSON and Markdown. This change adds no configuration or privileged operation, so no frontend or Lark companion is required. A shared Python composition helper was not added because the todo, risk, and summary facts differ and a parameter-heavy helper would not reduce decision ownership.