refactor(ai-roles): bake catalog URL at image build, 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 now fetches only
from an http(s):// base URL read from AI_AGENT_ROLES_CATALOG_URL; an empty or
non-http value yields a 502 (catalog unavailable). The default URL is baked
into the Docker image at build time and set per branch in CI.

- 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
  updated to reflect build-time injection, remote-only.
- Dockerfile: add ARG+ENV AI_AGENT_ROLES_CATALOG_URL in the installer stage.
- CI: develop.yml builds with the develop raw URL; release.yml (both build
  steps) with the main raw URL.
- 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

@@ -290,11 +290,12 @@ export class EnvironmentService {
   // ai_provider_credentials, with no env fallback. APP_SECRET stays (getAppSecret).
 
   getAiAgentRolesCatalogSource(): string {
-    // Catalog location. http(s):// URL => fetched remotely; anything else => a
-    // local filesystem directory. Defaults to the in-repo folder (dev). In prod
-    // set this to the raw GitHub base URL of the catalog repo. Unlike the AI_*
-    // getters above this is INFRA config (where the catalog lives), not
-    // provider/model config — so an env var here is appropriate.
+    // 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.
     return this.configService.get<string>('AI_AGENT_ROLES_CATALOG_URL', '');
   }