Productionize: back the cache with cas + anchored-chain; real strings.json catalog

[bdelanghe]

v0.1 is runnable (deterministic + Anthropic-on-miss + CAS-memoized). To productionize:

1. Back the store with cas behind the current get/put; record each audit as an anchored-chain derivation (content + auditVersion + model → signed, lineage-tracked result).
2. Point the catalog at the real brand/content/strings.json (add a type per symbol; extend the content schema).
3. Live-verify the Anthropic path with a key (the call + tool-use schema are implemented in anthropic.mjs).
4. Wire it into the brand-checks CI as an optional, keyed step (deterministic in PR; LLM nightly).
5. Budget integration with prx cost-vs-outcome.

[bdelanghe]

Real-catalog support landed (catalog.mjs): CATALOG=<path> node audit.mjs audits either the native catalog or a DTCG strings.json (type inferred from the key) — verified against the real @bounded-systems/brand content tokens.

Still open on #1: back the cache with the cas package + anchored-chain lineage (the fs store is the drop-in seam), source grounding from the real catalog/spec (currently demo-fixed), and live-verify the Anthropic path with a key.

[bdelanghe]

Store abstraction + cas/anchored-chain seam landed (store.mjs):

• Pluggable get/put/has. FsStore (default, verified — warm run = 0 calls) | CasStore.
• CasStore is shaped against the real APIs: cas BlobStore.put/get for result bytes, anchored-chain RefStore (key→digest) + DerivationStore.append (input→output lineage). STORE=cas enables it; graceful FsStore fallback when the packages aren't installed.
• Grounding externalized to grounding.json (GROUNDING=<path>).

Remaining to fully close #1:

1. Finalize CasStore factory wiring against the packages' concrete exported constructors (the port is correct; just the createBlobStore/createRefStore/createDerivationStore names), and add them as deps.
2. Source grounding per-catalog from the real spec/PDP.
3. Live-verify the Anthropic path with a key.

[bdelanghe]

cas/anchored-chain backing now works for real (store.mjs, STORE=cas):

• Implements the ports directly — cas BlobStore (content-addressed bytes; get re-hashes + rejects corrupt/absent), a ref layer (key→digest), and a derivation log in the anchored-chain DerivationStore.append shape (input(copy)→output(audit) lineage).
• Verified: warm run = 0 calls; 7 results → 3 blobs (identical audits dedupe — the CAS property); 7 lineage records.
• Per-catalog grounding: GROUNDING → catalog-sibling grounding.json → default.

Finding worth noting: @bounded-systems/cas exports the interface + sha256Hex/Digest, not a concrete store — so the right move was to implement the port (done), not import a store that doesn't exist.

Remaining: swap sha256Hex + the fs blob/derivation impls for the published packages (canonical digest + signed derivations) when they ship; live-verify the Anthropic path with a key. The architecture + lineage are in and verified.

[bdelanghe]

Done in v0.2.0: cas + anchored-chain wired from JSR (real content addressing + in-toto provenance), verified in CI via the room/socket store step. Live keyed Anthropic run is set up in .github/workflows/anthropic.yml — add the ANTHROPIC_API_KEY repo secret and trigger it. Remaining nicety (own follow-up): DSSE ed25519 signing of the derivation.