refactor(runtime)!: enforce durable protocol v3 boundaries

[WH-2099]

Summary

• Integrate the Driver protocol as a schema-first boundary across ingress, runtime state, persistence, artifacts, GraphQL, AG-UI, reconnect hydration, Web projection, and deployment safety.
• Preserve the public contract subsystem, the intentional CMA extension point, and existing prewarm behavior.
• Keep this PR in Draft until both the upstream repin and the production backup blocker are resolved.

Upstream checkpoint

The Driver has advanced to 3439bed72ad18ee6c295668117f88a66219ba45f in langgenius/mosoo-agent-driver#112.

That checkpoint updates Codex to 0.152.0, Claude Agent SDK to 0.3.257, Anthropic SDK to 0.123.0, and the strict contract wire grammar to protocol version 3.

This Mosoo branch still pins 5e661259e853663e561fed167aa495e792450045.

The previous Mosoo validation therefore does not cover the latest Driver checkpoint.

Before this PR can leave Draft, it must rebase current Mosoo main, pin the latest durable Driver commit, adapt every protocol version 3 boundary, and rerun the full repository check.

Production blocker

This PR remains Draft and must not be deployed to production.

Cloudflare Sandbox 0.12.9 does not expose an atomic writer freeze or forbidden-path backup primitive.

Repository code cannot prove that an active writer cannot recreate transient credentials between validation and backup capture.

No Driver workaround should weaken this safety boundary.

Historical validation

• The previous Driver pin passed the Mosoo full check with 41 of 41 tasks.
• The previous API run passed 1,899 tests with 0 failures and 7,125 assertions.
• The latest Driver checkpoint independently passes 1,666 tests with 0 failures, but has not yet been integrated into this branch.

Merge order

Driver PR #112 may merge first after its own CI is green.

This Mosoo PR must then pin the resulting durable Driver commit and revalidate the integration.

This Mosoo PR must not merge until the Cloudflare backup blocker is resolved and final CI is green.

Related work

• Closes refactor(runtime)!: enforce durable protocol v3 boundaries #586
• Upstream issue: refactor(runtime)!: enforce durable SDK protocol v3 boundaries mosoo-agent-driver#111
• Upstream implementation: refactor(runtime)!: enforce durable SDK protocol v3 boundaries mosoo-agent-driver#112

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[WH-2099]

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