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)

packages/aws-lambda/src/handler.test.ts

@@ -28,7 +28,7 @@ import {
   type PlanResult,
   type PlanV2ArtifactPublisher,
   type PlanV2Manifest,
-  publishPlanV2FromV1,
+  publishPlanV2FromExecutionPlan,
 } from "@hyperframes/producer/distributed";
 import { recomputePlanHashFromPlanDir } from "../../producer/src/services/render/stages/freezePlan.js";
 import type { AssembleEvent, LambdaEvent, PlanEvent, RenderChunkEvent } from "./events.js";
@@ -555,7 +555,7 @@ describe("handler dispatch", () => {
       ): Promise<PlanV2Manifest> => {
         const v1Dir = join(tmpRoot, `v1-${Date.now()}`);
         makeMinimalV1PlanDir(v1Dir, true);
-        const manifest = await publishPlanV2FromV1(v1Dir, publisher);
+        const manifest = await publishPlanV2FromExecutionPlan(v1Dir, publisher);
         expect(options.stagingParentDir).toBe(dirname(projectDir));
         expect(existsSync(join(dirname(projectDir), "plan-v2"))).toBe(false);
         return manifest;