fix: forward every documented Studio query filter and pin canonicalInputIdentity

Two review Minor findings against the brief itself, both closed:

- tests/mocks/handlers/tech-log-studio.ts silently dropped documented
  query filters instead of mirroring the mock gateway it wraps:
  listStudioDocuments forwarded only q/limit (dropping kind,
  publicationStatus, nextAction, projectId, sort, cursor),
  listStudioCatalog forwarded only type (dropping q/cursor/limit), and
  listStudioPublications ignored all four of its parameters outright.
  Added a shared queryParams() helper and forward every field each
  operation's projectRequest actually emits, plus a regression test
  that narrows the fixture set by kind through the real HTTP gateway
  (confirmed it fails without the fix).

- canonicalInputIdentity (on the idempotency-safety path, reused by
  Task 6) had no test. Added three tests against mutationIntent(): a
  large Korean payload stays within the byte bound, the same input
  retried twice yields an identical identity, and a mid-codepoint
  truncation cut leaves no replacement character (confirmed the third
  fails without the strip). The known collision limitation of any
  bounded-length identity scheme is documented in the test file rather
  than solved.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/mocks/handlers/tech-log-studio.ts

@@ -23,6 +23,30 @@ async function json(work: () => Promise<unknown>, status = 200) {
   }
 }
 
+/**
+ * Forwards every query parameter a `projectRequest` puts on the wire, not
+ * just the ones a first pass happened to reach for. A handler that silently
+ * drops a documented filter lets a later filter test pass for the wrong
+ * reason — it would observe the *unfiltered* mock result and never learn the
+ * parameter never left the URL.
+ */
+function queryParams(
+  url: URL,
+  stringNames: readonly string[],
+  numberNames: readonly string[] = [],
+): Record<string, string | number> {
+  const result: Record<string, string | number> = {};
+  for (const name of stringNames) {
+    const value = url.searchParams.get(name);
+    if (value !== null) result[name] = value;
+  }
+  for (const name of numberNames) {
+    const value = url.searchParams.get(name);
+    if (value !== null) result[name] = Number(value);
+  }
+  return result;
+}
+
 export function createTechLogStudioHandlers(
   gateway = createMockStudioGateway(),
   baseUrl = BASE,
@@ -47,12 +71,14 @@ export function createTechLogStudioHandlers(
       ),
       http.get(`${baseUrl}/api/v1/studio/documents`, ({ request }) => {
         const url = new URL(request.url);
-        const limit = url.searchParams.get("limit");
         return json(() =>
-          gateway.listDocuments({
-            ...(url.searchParams.get("q") ? { q: url.searchParams.get("q")! } : {}),
-            ...(limit ? { limit: Number(limit) } : {}),
-          } as never),
+          gateway.listDocuments(
+            queryParams(
+              url,
+              ["q", "kind", "publicationStatus", "nextAction", "projectId", "sort", "cursor"],
+              ["limit"],
+            ) as never,
+          ),
         );
       }),
       http.post(`${baseUrl}/api/v1/studio/documents`, async ({ request }) =>
@@ -117,9 +143,14 @@ export function createTechLogStudioHandlers(
             ),
           ),
       ),
-      http.get(`${baseUrl}/api/v1/studio/publications`, () =>
-        json(() => gateway.listPublications({})),
-      ),
+      http.get(`${baseUrl}/api/v1/studio/publications`, ({ request }) => {
+        const url = new URL(request.url);
+        return json(() =>
+          gateway.listPublications(
+            queryParams(url, ["q", "type", "cursor"], ["limit"]) as never,
+          ),
+        );
+      }),
       http.post(
         `${baseUrl}/api/v1/studio/publications/:publicationId/unpublish`,
         async ({ request, params }) =>
@@ -139,7 +170,9 @@ export function createTechLogStudioHandlers(
       http.get(`${baseUrl}/api/v1/studio/catalog`, ({ request }) => {
         const url = new URL(request.url);
         return json(() =>
-          gateway.getCatalog({ type: url.searchParams.get("type") as never }),
+          gateway.getCatalog(
+            queryParams(url, ["type", "q", "cursor"], ["limit"]) as never,
+          ),
         );
       }),
     ],