refactor(producer): share plan execution builder (#2906)

## What

Refactor distributed planning around one shared local execution-plan builder:

- `buildLocalExecutionPlan()` now owns compile/probe/extract/audio/freeze.
- Legacy `plan()` remains a deprecated v1 transport wrapper.
- Plan v2 calls the shared builder directly and publishes through the existing manifest/CAS contract.
- Add neutral `createPlanV2FromExecutionPlan()`, `publishPlanV2FromExecutionPlan()`, `getPlanV2ExecutionPlanHash()`, and `PLAN_PROTOCOL_V1` names.
- Retain deprecated v1-named exports and wire aliases.
- Recommend explicit Plan v2 opt-in for new producer, Lambda, and Cloud Run integrations.

## Why

Plan v2 previously looked like it invoked a v1 planner even though v1 and v2 share the same frozen local execution representation. This removes that migration-era coupling while preserving the public minor-version compatibility contract.

## How

The shared builder returns neutral internal execution-plan fields. The v1 wrapper maps those fields back to the existing `PlanResult`; the v2 publisher consumes them directly.

Compatibility is intentional and covered by exact shape tests:

- omitted `planProtocol` still serializes/selects `"v1"`;
- v1 layouts, descriptor-less decoding, event unions, workflow branches, and exports remain;
- the v1 descriptor JSON is byte-identical and `CURRENT_PLAN_PROTOCOL` is an identity-preserving alias;
- v2 manifest bytes, key order, hash framing, and `sourcePlanV1Hash` wire key remain unchanged;
- no enumerable neutral hash field was added to manifests or returned result objects;
- v1/v2 result objects, cloud event payloads, and SDK handle key sets remain unchanged.

## Test plan

- Focused Plan v1/v2/protocol/export/size compatibility: 141 passed
- `@hyperframes/core`: 1,419 passed
- `@hyperframes/producer` unit lane: 990 passed
- `@hyperframes/aws-lambda`: 140 passed
- `@hyperframes/gcp-cloud-run`: 101 passed
- Producer, Lambda, and Cloud Run typechecks
- Repository-wide lint, format check, workspace/package-subpath checks
- Full workspace build
- `git diff --check`

- [x] Unit tests added/updated
- [ ] Manual testing performed
- [x] Documentation updated (if applicable)

examples/aws-lambda/README.md

@@ -75,7 +75,7 @@ aws stepfunctions start-execution \
   "ProjectS3Uri": "s3://${RENDER_BUCKET}/projects/my-project.tar.gz",
   "PlanOutputS3Prefix": "s3://${RENDER_BUCKET}/renders/$(date +%s)/",
   "OutputS3Uri": "s3://${RENDER_BUCKET}/output.mp4",
-  "PlanProtocol": "v1",
+  "PlanProtocol": "v2",
   "Config": {
     "fps": 30,
     "width": 1920,
@@ -92,7 +92,8 @@ EOF
 
 The Step Functions execution kicks off Plan, fans out RenderChunk via
 the Map state, and finally Assemble. Final mp4 lands at `OutputS3Uri`.
-`PlanProtocol` may be `"v1"` or `"v2"`; absent defaults to v1. V2 uses
+Plan v2 is recommended for new integrations. `PlanProtocol` may be `"v1"` or
+`"v2"`; absent still defaults to v1 for backwards compatibility. V2 uses
 separate manifest and content-addressed artifact locators throughout the
 workflow and never places a v2 object in `PlanS3Uri`.