feat: WeKan ticketing source

- wekan connector: board id as project key, cards assigned to the
  consultant's WeKan username (assignees with member fallback), archived
  cards skipped, client-side modifiedAt since-filtering, username/password
  login with token reuse (or pre-issued token), case-insensitive identity
- fake-WeKan unit tests: factory validation, test-connection, fetch
  filtering, key listing, token reuse
- admin customer wizard: WeKan option + credential fields
- OpenAPI enum + credential shapes, README identity mapping docs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/templates/admin.html

@@ -31,6 +31,7 @@
             <option value="jira">Jira Cloud</option>
             <option value="azure_devops">Azure DevOps</option>
             <option value="youtrack">YouTrack</option>
+            <option value="wekan">WeKan</option>
             <option value="demo">Demo (offline)</option>
           </select>
         </div>
@@ -58,6 +59,12 @@
         <legend>YouTrack credentials</legend>
         <div class="field"><label for="c-yt-token">Permanent token</label><input type="password" id="c-yt-token" autocomplete="off"></div>
       </fieldset>
+      <fieldset id="creds-wekan" class="creds" hidden>
+        <legend>WeKan credentials</legend>
+        <p class="hint">Project key above = the WeKan board id; the connector imports cards assigned to each consultant's WeKan username.</p>
+        <div class="field"><label for="c-wekan-user">Username</label><input type="text" id="c-wekan-user" autocomplete="off"></div>
+        <div class="field"><label for="c-wekan-pass">Password</label><input type="password" id="c-wekan-pass" autocomplete="off"></div>
+      </fieldset>
       <fieldset id="creds-demo" class="creds" hidden>
         <legend>Demo</legend>
         <p class="hint">No credentials required — tickets are fabricated locally.</p>