🐛 fix: complete Effect 4 runtime compatibility

[N0xMare]

Summary

• complete the Effect 4 beta.102 workflow bridge, SingleRunner, managed-runtime, callback, cancellation, schema, metric, and service-tag migrations
• make child-process timeout and interruption cleanup bounded and descendant-safe across POSIX, with guarded and bounded taskkill fallback behavior on Windows
• migrate sandbox entities and transports while preserving their public service-key declarations
• update VCS execution to ChildProcessSpawner, harden jj timeouts and cleanup, and align public declarations and docs
• align observability log levels, ServiceClass tags, metric APIs, public logging exports, generated declarations, and contract tests
• refresh generated declarations and documentation mirrors required by the corrected public APIs

Why this belongs together

The original Workflow.make repair exposed the adjacent Effect 4 runtime and declaration incompatibilities that prevented the bridge from operating reliably end to end. This update keeps those compatibility repairs together while excluding generic checkpoint and Nanocodex backend feature work.

Verification

• root typecheck, lint/format, declaration consistency, and declaration consumer checks pass
• driver: 199 pass, including bounded Windows taskkill fallback and actual target termination
• sandbox: 198 pass, 2 intentional environment skips; emitted-declaration consumer compile passes
• memory: 165 pass; emitted service-key declarations pass the strict consumer gate
• observability: 334 pass
• VCS: 95 pass
• server: 714 pass, 1 skip
• smithers facade: 310 pass, 7 skip
• CLI: all 218 test batches pass
• docs/llms artifacts regenerated; workspace declarations rebuilt, with the CLI build passing under an expanded Node heap
• frozen pnpm and Bun lockfile verification passes
• CI, fault injection, and automated review all pass on the rebased head

Stack and merge order

This is layer 1 of 3 in the current compatibility/feature stack:

1. 🐛 fix: complete Effect 4 runtime compatibility #1463 — Effect 4 runtime compatibility (this PR), head 7bb8e91b209efb30ce7f0f60bab9b7599292762d
2. feat: add durable generic agent checkpoints #1449 — durable generic agent checkpoints, head f0c287dfb5c0f37f4657d25148c8ef5bc4cb6f30
3. feat: add Nanocodex agent backend #1461 — Nanocodex backend, head f9a247f9c82033ab2cdaf6034c76e85b0dd35f00

Merge in that order. Because these are cross-repository PRs, all three bases intentionally remain main; the later PR diffs are cumulative until their predecessors land.