fix(devtools,world-model): resolve atomic fingerprint to artifact version in store and inspector

[Adityakk9031]

Summary

Fixes a critical disconnect in the DevTools S4 inspector where clicking through DAG / timeline frames fails with 404 Not Found whenever a node's @atomic fingerprint differs from the store's serialized artifact version.

Root Cause

1. In the DevTools frontend and replay session, each timeline frame records atomicVersion: receipt.fingerprints["@atomic"].
2. When an operator clicks a node in the inspector (S4 click-through), DevTools issues a GET request to /api/node/:id?version=<atomicVersion>.
3. In FileSystemWorldModelStore and InMemoryWorldModelStore, commits were persisted and keyed strictly by raw artifact content address version = contentAddressOf(serializeArtifact(files)) (stored under versions/<contentAddress>.bin).
4. Whenever a node defines a canonicalizer where the @atomic fingerprint differs from the whole-artifact byte hash (such as subset facet indexing, projection normalization, or custom canonicalizers), store.readVersion(node, atomicVersion) returned null.
5. DevTools server caught this and returned 404 Not Found ({"error": "no world-model for node@version"}), completely breaking the S4 click-through inspector for those nodes.

Changes

1. packages/reactor/src/world-model/fs-store.ts:
   • In commitPublished: When fingerprints[ATOMIC_FACET] differs from version, an alias pointer file is written atomically at versions/<atomicFp>.alias containing the canonical artifact version address.
   • In readVersion: If versions/<version>.bin is not found, check versions/<version>.alias and dereference to the artifact version. Also checks published.json pointer if it matches the current published atomic facet.
2. packages/reactor/src/world-model/store.ts:
   • Documented that readVersion accepts either artifact content address or atomic facet fingerprint.
   • Added #aliases map to InMemoryWorldModelStore and fallback alias resolution to match filesystem store semantics.
3. packages/reactor-devtools/src/data/index.ts:
   • readNodeWorldModel: Added defensive fallback against published pointer.
   • openWorldModels: Added support for both world-models/ and world-model/ directories.
4. packages/reactor-devtools/src/server/index.ts:
   • Updated parameter documentation and 400 error messaging for ?version=.
5. Tests:
   • Added packages/reactor/src/world-model/__tests__/fs-store-alias.test.ts testing alias resolution across both FileSystemWorldModelStore and InMemoryWorldModelStore.
   • Added integration test in packages/reactor-devtools/src/server/server.test.ts ensuring GET /api/node/:id?version=<atomicVersion> returns 200 and loads the node's world-model when the atomic fingerprint differs from the artifact version.

Verification

• node --test packages/reactor/dist/world-model/__tests__/fs-store-alias.test.js (2/2 passing)
• node --test packages/reactor-devtools/dist/server/server.test.js (8/8 passing)
• node --test packages/reactor-devtools/dist/data/*.test.js (33/33 passing)
• node --test tools/eval-harness/eval-harness.test.mjs (10/10 passing)
• Synthetic reproduction scenario verifying transition from 404 to 200 with artifact files loaded.

[Adityakk9031]

@josemontesdeoca have a look