refactor(ai-roles): make catalog URL a per-branch image default, drop local-fs source

The agent-roles catalog source is no longer hardcoded in app code and no longer
supports a local filesystem directory. The provider fetches only from an
http(s):// base URL read at runtime from AI_AGENT_ROLES_CATALOG_URL; an empty or
non-http value yields a 502 (catalog unavailable). The image ships a per-branch
default for that URL (set in CI), still overridable at runtime via the env var.

- provider: drop readLocal + node:fs/node:path; readRelative requires http(s)
  and 502s otherwise; remote fetch/streaming-cap/SSRF guards unchanged.
- environment.service: keep AI_AGENT_ROLES_CATALOG_URL (default ''); comment
  reflects the per-branch build-time default that is runtime-overridable.
- Dockerfile: add ARG+ENV AI_AGENT_ROLES_CATALOG_URL in the installer stage as
  the image default.
- CI: develop.yml builds with the develop raw URL; release.yml defines the main
  raw URL once in workflow env and references it from both build steps.
- tests: replace local-fixture tests with remote-mock happy/malformed bundle
  tests and a non-http => 502 case; path-traversal block uses an https source.
- docs: update .env.example, CHANGELOG (#222), agent-roles-catalog/README.

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

apps/server/src/integrations/environment/environment.service.ts

@@ -291,11 +291,13 @@ export class EnvironmentService {
 
   getAiAgentRolesCatalogSource(): string {
     // Catalog location: an http(s):// base URL the catalog is fetched from.
-    // The value is baked into the image at build time (Dockerfile ARG
-    // AI_AGENT_ROLES_CATALOG_URL, set per-branch in CI); local-filesystem
-    // sources are no longer supported. Empty/unset => the catalog is
-    // unavailable (the provider returns 502). This is INFRA config (where the
-    // catalog lives), not provider/model config, so an env var is appropriate.
+    // The image ships a per-branch default for this baked in at build time
+    // (Dockerfile ARG AI_AGENT_ROLES_CATALOG_URL, set per-branch in CI), but it
+    // is overridable at runtime via the env var (this getter returns that
+    // runtime value). Local-filesystem sources are no longer supported.
+    // Empty/unset => the catalog is unavailable (the provider returns 502).
+    // This is INFRA config (where the catalog lives), not provider/model
+    // config, so an env var is appropriate.
     return this.configService.get<string>('AI_AGENT_ROLES_CATALOG_URL', '');
   }