Resolve final review blockers

[fitchmultz]

Summary

Addresses the withheld approval review for v0.1.20..HEAD.

• Splits provider turn data into narrow sendRequest, finalizeInputs, and terminalResources; send now returns only send-owned facts.
• Moves transcript message-offset lookup out of finalize internals into a send-layer helper.
• Centralizes terminal event ownership in CursorRunFinalizer, including atomic fallback handling when direct terminal emission fails before pushing a terminal event.
• Derives transcript display spec keys and replay summaries from the canonical tool registry instead of keeping duplicate summary policy in transcript specs.
• Removes stale transcript summarize* replay helpers.
• Fixes cursor-sdk-output-filter.d.mts to match runtime string patterns and adds export-map checks for every published .d.mts surface.
• Validates debug-provider-events capture summaries before returning required declaration fields.
• Splits the kitchen-sink test/helpers/pi-harness.ts into event, context, model, tool, registration, and type fixture modules while preserving the public helper barrel.
• Keeps prior fixes for replay detail separation, smoke timeout status capture, package declaration shipping, duplicate classifier removal, and behavior-level MCP timeout tests.

Validation

• npm run typecheck
• npm test — 69 files / 585 tests
• git diff --check
• npm pack --dry-run — includes all shipped declaration-backed .mjs declarations
• PI_LIVE_TIMEOUT=240 npm run smoke:isolated — basic provider, native replay, and plan-strip replay passed with clean replay-error scans
• Thermo-nuclear review — ZERO FINDINGS