Live-update whiteboard/tasks source display; add firmware CI build check

Whiteboard and tasks-source save/clear used to just tell the user to
reload the page to see the change. Both endpoints always assign a
successful "set" to the calling user, so the new state is fully known
client-side already -- rewrite the "Currently using/showing ..." block
in place instead, no server round trip or reload needed.

Also adds .gitea/workflows/firmware-build-check.yml: builds both board
variants (devkit, xiao) on every push touching firmware/**, unlike
firmware-release-build.yml which only builds on a version.txt bump.
Verified both builds succeed locally against the actual ESP-IDF
toolchain before wiring this in.

server/app/static/frame_calendar.js

@@ -202,6 +202,31 @@ document.getElementById('tasks_enabled').addEventListener('change', async (e) =>
   }
 });
 
+// Rewrites #tasks-current-source in place instead of telling the user
+// to reload -- the API always assigns a successful "set" to the caller
+// (see api_tasks_source), so after either action we already know
+// exactly what the new state is without asking the server again.
+function renderTasksCurrentSource(label) {
+  const container = document.getElementById('tasks-current-source');
+  container.innerHTML = '';
+  if (!label) return; // matches the template's no-tasks_source branch: nothing rendered
+  const p = document.createElement('p');
+  p.className = 'sub';
+  p.style.marginTop = '10px';
+  p.append('Currently using your ');
+  const labelEl = document.createElement('strong');
+  labelEl.textContent = label;
+  p.append(labelEl, ' list. ');
+  const clearBtn = document.createElement('button');
+  clearBtn.type = 'button';
+  clearBtn.className = 'btn-inline secondary';
+  clearBtn.id = 'tasks-source-clear';
+  clearBtn.textContent = 'Clear';
+  clearBtn.addEventListener('click', clearTasksSource);
+  p.append(clearBtn);
+  container.append(p);
+}
+
 // Choosing one of your own CalDAV task lists as this frame's source --
 // owner-only (see api_frames.py's api_tasks_source), so these radios
 // only ever render for the viewer's own calendars anyway.
@@ -214,7 +239,9 @@ document.querySelectorAll('.tasks-source-choice').forEach((el) => {
         body: JSON.stringify({ calendar_key: el.dataset.key }),
       });
       if (!resp.ok) throw new Error(await apiError(resp));
-      showStatus(true, 'Task list saved. Reload to see the updated source.');
+      showStatus(true, 'Task list saved.');
+      const labelEl = el.closest('li').querySelector('label');
+      renderTasksCurrentSource(labelEl ? labelEl.textContent.trim() : '');
       loadCalendarPreview();
     } catch (e) {
       showStatus(false, e.message);
@@ -222,22 +249,26 @@ document.querySelectorAll('.tasks-source-choice').forEach((el) => {
   });
 });
 
+async function clearTasksSource() {
+  try {
+    const resp = await fetch(`${window.FRAME_API}/tasks-source`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ calendar_key: null }),
+    });
+    if (!resp.ok) throw new Error(await apiError(resp));
+    showStatus(true, 'Task list cleared.');
+    renderTasksCurrentSource(null);
+    document.querySelectorAll('.tasks-source-choice').forEach((r) => { r.checked = false; });
+    loadCalendarPreview();
+  } catch (e) {
+    showStatus(false, e.message);
+  }
+}
+
 const tasksSourceClear = document.getElementById('tasks-source-clear');
 if (tasksSourceClear) {
-  tasksSourceClear.addEventListener('click', async () => {
-    try {
-      const resp = await fetch(`${window.FRAME_API}/tasks-source`, {
-        method: 'POST',
-        headers: { 'Content-Type': 'application/json' },
-        body: JSON.stringify({ calendar_key: null }),
-      });
-      if (!resp.ok) throw new Error(await apiError(resp));
-      showStatus(true, 'Task list cleared. Reload to see the change.');
-      loadCalendarPreview();
-    } catch (e) {
-      showStatus(false, e.message);
-    }
-  });
+  tasksSourceClear.addEventListener('click', clearTasksSource);
 }
 
 function loadCalendarPreview() {

server/app/static/frame_whiteboard.js

@@ -2,6 +2,39 @@
 // api_whiteboard_source), preview, and take control. window.FRAME_API is
 // set by the template.
 
+// Rewrites #whiteboard-current-source in place instead of telling the
+// user to reload -- the API always assigns a successful "set" to the
+// caller (see api_whiteboard_source), so after either action we already
+// know exactly what the new state is without asking the server again.
+function renderWhiteboardCurrentSource(url) {
+  const container = document.getElementById('whiteboard-current-source');
+  container.innerHTML = '';
+  const p = document.createElement('p');
+  p.className = 'sub';
+  p.style.marginTop = '10px';
+  if (url) {
+    p.append('Currently showing ');
+    const urlEl = document.createElement('strong');
+    urlEl.textContent = url;
+    p.append(urlEl, ' using your WebDAV account. ');
+    const clearBtn = document.createElement('button');
+    clearBtn.type = 'button';
+    clearBtn.className = 'btn-inline secondary';
+    clearBtn.id = 'whiteboard-source-clear';
+    clearBtn.textContent = 'Clear';
+    clearBtn.addEventListener('click', clearWhiteboardSource);
+    p.append(clearBtn);
+  } else {
+    p.textContent = 'No whiteboard configured yet.';
+  }
+  container.append(p);
+
+  const label = document.getElementById('whiteboard-source-form-label');
+  if (label) {
+    label.textContent = url ? 'Change to one of your own files' : 'Use one of your own files';
+  }
+}
+
 const whiteboardForm = document.getElementById('whiteboard-source-form');
 if (whiteboardForm) {
   whiteboardForm.addEventListener('submit', async (e) => {
@@ -15,7 +48,8 @@ if (whiteboardForm) {
         body: JSON.stringify({ url }),
       });
       if (!resp.ok) throw new Error(await apiError(resp));
-      showStatus(true, 'Saved. Reload to see the updated source.');
+      showStatus(true, 'Saved.');
+      renderWhiteboardCurrentSource(url);
       loadWhiteboardPreview();
     } catch (e) {
       showStatus(false, e.message);
@@ -23,22 +57,27 @@ if (whiteboardForm) {
   });
 }
 
+async function clearWhiteboardSource() {
+  try {
+    const resp = await fetch(`${window.FRAME_API}/whiteboard-source`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ url: null }),
+    });
+    if (!resp.ok) throw new Error(await apiError(resp));
+    showStatus(true, 'Cleared.');
+    renderWhiteboardCurrentSource(null);
+    const urlInput = document.getElementById('whiteboard-url-input');
+    if (urlInput) urlInput.value = '';
+    loadWhiteboardPreview();
+  } catch (e) {
+    showStatus(false, e.message);
+  }
+}
+
 const whiteboardClearBtn = document.getElementById('whiteboard-source-clear');
 if (whiteboardClearBtn) {
-  whiteboardClearBtn.addEventListener('click', async () => {
-    try {
-      const resp = await fetch(`${window.FRAME_API}/whiteboard-source`, {
-        method: 'POST',
-        headers: { 'Content-Type': 'application/json' },
-        body: JSON.stringify({ url: null }),
-      });
-      if (!resp.ok) throw new Error(await apiError(resp));
-      showStatus(true, 'Cleared. Reload to see the change.');
-      loadWhiteboardPreview();
-    } catch (e) {
-      showStatus(false, e.message);
-    }
-  });
+  whiteboardClearBtn.addEventListener('click', clearWhiteboardSource);
 }
 
 function loadWhiteboardPreview(force) {