feat: cache canned responses and agents in IndexedDB

Converts the canned-response and agent API clients to CacheEnabledApiClient
subclasses and wires revalidate actions into the corresponding Vuex modules,
so settings pages and pickers stop fetching the same lists on every visit.
The canned-response search box continues to bypass the cache and hit the
network directly, so server-side ordering stays authoritative.

Also fixes a pre-existing gap in teams/revalidate: SET_TEAMS merges into a
record dict by id and never removes missing entries, so a team deleted
server-side would survive a reconnect-driven revalidate. Now matches the
get action by emitting CLEAR_TEAMS first.

Each affected spec clears its IDB store before every case, since the
preflight-throws-on-axios-reject pattern they relied on is going away in the
next commit.

app/javascript/dashboard/api/agents.js

@@ -1,12 +1,27 @@
 /* global axios */
 
-import ApiClient from './ApiClient';
+import CacheEnabledApiClient from './CacheEnabledApiClient';
 
-class Agents extends ApiClient {
+class Agents extends CacheEnabledApiClient {
   constructor() {
     super('agents', { accountScoped: true });
   }
 
+  // eslint-disable-next-line class-methods-use-this
+  get cacheModelName() {
+    return 'account_user';
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  extractDataFromResponse(response) {
+    return response.data;
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  marshallData(dataToParse) {
+    return { data: dataToParse };
+  }
+
   bulkInvite({ emails }) {
     return axios.post(`${this.url}/bulk_create`, {
       emails,

app/javascript/dashboard/api/cannedResponse.js

@@ -1,15 +1,32 @@
 /* global axios */
 
-import ApiClient from './ApiClient';
+import CacheEnabledApiClient from './CacheEnabledApiClient';
 
-class CannedResponse extends ApiClient {
+class CannedResponse extends CacheEnabledApiClient {
   constructor() {
     super('canned_responses', { accountScoped: true });
   }
 
-  get({ searchKey }) {
-    const url = searchKey ? `${this.url}?search=${searchKey}` : this.url;
-    return axios.get(url);
+  // eslint-disable-next-line class-methods-use-this
+  get cacheModelName() {
+    return 'canned_response';
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  extractDataFromResponse(response) {
+    return response.data;
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  marshallData(dataToParse) {
+    return { data: dataToParse };
+  }
+
+  get({ searchKey } = {}) {
+    if (searchKey) {
+      return axios.get(`${this.url}?search=${searchKey}`);
+    }
+    return super.get(true);
   }
 }