fix: migrate schema $id base to live github pages registry

Rewrite every JSON-Schema $id and $ref off the phantom domain
schemas.coding-autopilot.dev to the live, org-controlled GitHub Pages
registry base that actually resolves 200:
https://coding-autopilot-system.github.io/cas-contracts/registry/

The version paths (v0.1/v1.0/v1.1 and the immutable releases/ tree) are
unchanged; only the domain moves, so each $id now dereferences directly to
the schema it identifies. Updates the scripts/lib.mjs $id base used by the
example validator, the vendored example artifact uris, the contract test
expectations, and docs/DISTRIBUTION.md (the canonical-namespace/custom-domain
guidance is superseded now that $id == hosting URL).

npm ci && npm test (35 pass), validate:registry (3 releases / 3 lines) and
validate (7 examples) all green after regenerating the registry manifests
with the new content hashes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Aitomates

docs/DISTRIBUTION.md

@@ -7,7 +7,7 @@ sub-path of the documentation site on a single GitHub Pages origin:
 https://coding-autopilot-system.github.io/cas-contracts/registry/
 ```
 
-Schema `$id` values use the reserved canonical namespace `https://schemas.coding-autopilot.dev/`. This namespace is the stable *identity* of each schema and is independent of where the schema is hosted. Until DNS is configured for that domain, consumers must resolve schemas from the live GitHub Pages distribution URL above.
+Schema `$id` values use the live GitHub Pages registry base `https://coding-autopilot-system.github.io/cas-contracts/registry/`, so every `$id` resolves directly to the schema it identifies. Identity and hosting location are the same URL; consumers can dereference an `$id` to fetch the schema.
 
 ## URL Contract
 
@@ -51,19 +51,11 @@ a schema tag can no longer clobber each other on the single Pages origin.
 
 Repository administrators must configure GitHub Pages to use **GitHub Actions** as its source. Publication uses GitHub's OIDC token and does not require stored deployment credentials.
 
-## Custom domain (manual follow-up)
-
-Serving the registry under the canonical `schemas.coding-autopilot.dev` `$id`
-namespace requires infrastructure that cannot be provisioned from this
-repository:
-
-1. Configure DNS for `schemas.coding-autopilot.dev` (a `CNAME` to
-   `coding-autopilot-system.github.io`, or the four GitHub Pages `A`/`AAAA`
-   apex records) with the domain registrar.
-2. Because the single Pages origin now hosts the documentation at its root and
-   the registry under `/registry/`, a custom domain would remap the **entire**
-   origin — it cannot point only at the `/registry/` sub-path. Activating
-   `schemas.coding-autopilot.dev` therefore requires a dedicated hosting origin
-   for the registry (for example, a separate Pages project or a CDN) rather than
-   the shared docs site. Until such an origin exists, resolve schemas from the
-   GitHub Pages URL above.
+## Custom domain (optional future work)
+
+Schema `$id` values resolve on the live GitHub Pages origin today, so no DNS or
+custom-domain work is required for schemas to dereference. A vanity domain (for
+example `schemas.coding-autopilot.dev`) would only be a cosmetic rename of the
+`$id` base and, if ever adopted, would require its own hosting origin plus a
+coordinated `$id` migration across this repository and every consumer that
+vendors these schemas. It is intentionally out of scope here.

examples/v0.1/artifact-manifest.json

@@ -11,7 +11,7 @@
   "artifacts": [
     {
       "kind": "schema",
-      "uri": "https://schemas.coding-autopilot.dev/v0.1/prompt-envelope.schema.json",
+      "uri": "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/prompt-envelope.schema.json",
       "sha256": "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
     }
   ]

examples/v1.0/artifact-manifest.json

@@ -11,7 +11,7 @@
   "artifacts": [
     {
       "kind": "schema",
-      "uri": "https://schemas.coding-autopilot.dev/v1.0/prompt-envelope.schema.json",
+      "uri": "https://coding-autopilot-system.github.io/cas-contracts/registry/v1.0/prompt-envelope.schema.json",
       "sha256": "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
     }
   ]

schemas/v0.1/artifact-manifest.schema.json

@@ -1,6 +1,6 @@
 {
     "$schema":  "https://json-schema.org/draft/2020-12/schema",
-    "$id":  "https://schemas.coding-autopilot.dev/v0.1/artifact-manifest.schema.json",
+    "$id":  "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/artifact-manifest.schema.json",
     "title":  "ArtifactManifest",
     "type":  "object",
     "allOf":  [

schemas/v0.1/common.schema.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://json-schema.org/draft/2020-12/schema",
-  "$id": "https://schemas.coding-autopilot.dev/v0.1/common.schema.json",
+  "$id": "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/common.schema.json",
   "title": "CAS Common Definitions",
   "$defs": {
     "actor": {

schemas/v0.1/evaluation-result.schema.json

@@ -1,6 +1,6 @@
 {
     "$schema":  "https://json-schema.org/draft/2020-12/schema",
-    "$id":  "https://schemas.coding-autopilot.dev/v0.1/evaluation-result.schema.json",
+    "$id":  "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/evaluation-result.schema.json",
     "title":  "EvaluationResult",
     "type":  "object",
     "allOf":  [

schemas/v0.1/policy-decision.schema.json

@@ -1,6 +1,6 @@
 {
     "$schema":  "https://json-schema.org/draft/2020-12/schema",
-    "$id":  "https://schemas.coding-autopilot.dev/v0.1/policy-decision.schema.json",
+    "$id":  "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/policy-decision.schema.json",
     "title":  "PolicyDecision",
     "type":  "object",
     "allOf":  [

schemas/v0.1/prompt-envelope.schema.json

@@ -1,6 +1,6 @@
 {
     "$schema":  "https://json-schema.org/draft/2020-12/schema",
-    "$id":  "https://schemas.coding-autopilot.dev/v0.1/prompt-envelope.schema.json",
+    "$id":  "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/prompt-envelope.schema.json",
     "title":  "PromptEnvelope",
     "type":  "object",
     "allOf":  [

schemas/v0.1/run-event.schema.json

@@ -1,6 +1,6 @@
 {
     "$schema":  "https://json-schema.org/draft/2020-12/schema",
-    "$id":  "https://schemas.coding-autopilot.dev/v0.1/run-event.schema.json",
+    "$id":  "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/run-event.schema.json",
     "title":  "RunEvent",
     "type":  "object",
     "allOf":  [

schemas/v0.1/verification-result.schema.json

@@ -1,6 +1,6 @@
 {
     "$schema":  "https://json-schema.org/draft/2020-12/schema",
-    "$id":  "https://schemas.coding-autopilot.dev/v0.1/verification-result.schema.json",
+    "$id":  "https://coding-autopilot-system.github.io/cas-contracts/registry/v0.1/verification-result.schema.json",
     "title":  "VerificationResult",
     "type":  "object",
     "allOf":  [