fix(context): use repo-scoping /scope/context endpoint

Cherry-picked from stale branch codex/wp-0012-scope-context (9709692).
main was still calling the old /repos/{slug}/scope path; repo-scoping now
serves GET /repos/{slug}/scope/context (web_api/app.py:1449). Includes the
resolver test and consistent workplan-doc updates. Test: 2 passed.

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

src/activity_core/context_resolvers/repo_scoping.py

@@ -2,7 +2,7 @@
 
 Registered as source type 'repo-scoping'.
 Supported queries:
-  - repo_profile: GET {REPO_SCOPING_URL}/repos/{repo_slug}/scope
+  - repo_profile: GET {REPO_SCOPING_URL}/repos/{repo_slug}/scope/context
 
 5-minute in-process cache keyed by (query, repo_slug). Cache is per-worker-
 process; not shared across Temporal workers.
@@ -36,7 +36,7 @@ class RepoScopingContextResolver(ContextResolver):
                 ts, val = _CACHE[cache_key]
                 if now - ts < _CACHE_TTL:
                     return val
-            url = f"{_REPO_SCOPING_URL.rstrip('/')}/repos/{repo_slug}/scope"
+            url = f"{_REPO_SCOPING_URL.rstrip('/')}/repos/{repo_slug}/scope/context"
             resp = httpx.get(url, timeout=10.0)
             resp.raise_for_status()
             result: dict[str, Any] = resp.json()