Three features: device dropdown filter, charge log history, unassign-all

- Device dropdowns (quick-assign, bulk install, assign page) now only show
  devices with free slots; full devices are excluded entirely
- New ChargeLog model tracks charge dates with optional cycle increment;
  battery detail page gets a Charge History card with add/delete rows
- Device list page gets per-device Unassign All button (with confirmation)
  via new POST /device/<id>/unassign-all route

templates/assign.html

@@ -11,23 +11,16 @@
       <div class="form-group">
         <label>Select Device</label>
         {% for device in devices %}
-          {% set full = device.installed_count() >= device.battery_slots %}
-          {% set mix  = device.installed_brands() and battery.brand not in device.installed_brands() %}
-          <div class="device-option" style="margin-bottom:0.75rem;padding:0.75rem;border:1px solid #e2e8f0;border-radius:4px;
-                      {% if full %}opacity:0.5;{% endif %}background:#fff;">
-            <label style="display:flex;align-items:center;gap:0.6rem;font-weight:normal;min-height:44px;cursor:{% if full %}not-allowed{% else %}pointer{% endif %};">
-              <input type="radio" name="device_id" value="{{ device.id }}"
-                     {% if full %}disabled{% endif %}
-                     style="cursor:{% if full %}not-allowed{% else %}pointer{% endif %};">
+          {% set mix = device.installed_brands() and battery.brand not in device.installed_brands() %}
+          <div class="device-option" style="margin-bottom:0.75rem;padding:0.75rem;border:1px solid #e2e8f0;border-radius:4px;background:#fff;">
+            <label style="display:flex;align-items:center;gap:0.6rem;font-weight:normal;min-height:44px;cursor:pointer;">
+              <input type="radio" name="device_id" value="{{ device.id }}" style="cursor:pointer;">
               <span>
                 <strong>{{ device.name }}</strong>
                 <span class="text-muted">({{ device.installed_count() }}/{{ device.battery_slots }} slots used)</span>
-                {% if full %}
-                  <span class="badge badge-retired">Full</span>
-                {% endif %}
               </span>
             </label>
-            {% if mix and not full %}
+            {% if mix %}
               <p class="text-warning" style="margin-top:0.3rem;margin-left:1.6rem;">
                 ⚠ Already has {{ device.installed_brands()|join(', ') }} — mixing brands not recommended.
               </p>
@@ -42,7 +35,7 @@
       </div>
     </form>
   {% else %}
-    <p class="text-muted">No devices exist yet. <a href="{{ url_for('device_add') }}">Add a device first.</a></p>
+    <p class="text-muted">No devices with free slots. <a href="{{ url_for('device_add') }}">Add a device</a> or free up slots first.</p>
   {% endif %}
 </div>
 {% endblock %}

templates/battery_detail.html

@@ -148,6 +148,66 @@
   </form>
 </div>
 
+<!-- Charge History -->
+<div class="card">
+  <h2>Charge History</h2>
+
+  {% if charge_logs %}
+  <div class="table-wrap">
+    <table class="responsive-table">
+      <thead>
+        <tr>
+          <th>Date</th>
+          <th>+Cycle</th>
+          <th>Notes</th>
+          <th></th>
+        </tr>
+      </thead>
+      <tbody>
+        {% for log in charge_logs %}
+        <tr>
+          <td data-label="Date">{{ log.charged_date }}</td>
+          <td data-label="+Cycle">{{ '✓' if log.increment_cycles else '—' }}</td>
+          <td data-label="Notes" class="text-muted">{{ log.notes or '—' }}</td>
+          <td data-label="">
+            <form class="inline" method="post"
+                  action="{{ url_for('battery_charge_log_delete', battery_id=battery.id, log_id=log.id) }}"
+                  onsubmit="return confirm('Delete this charge log entry?')">
+              <button class="btn btn-sm btn-danger" type="submit">Delete</button>
+            </form>
+          </td>
+        </tr>
+        {% endfor %}
+      </tbody>
+    </table>
+  </div>
+  {% else %}
+  <p class="text-muted" style="margin-bottom:0.75rem;">No charge log entries yet.</p>
+  {% endif %}
+
+  <h3 style="font-size:1rem;margin:1rem 0 0.5rem;color:var(--text-h2);">Add Charge Entry</h3>
+  <form method="post" action="{{ url_for('battery_charge_log_add', battery_id=battery.id) }}"
+        style="display:flex;gap:0.5rem;flex-wrap:wrap;align-items:flex-end;">
+    <div class="form-group" style="margin:0;flex:1;min-width:140px;">
+      <label>Date</label>
+      <input type="date" name="charged_date" required>
+    </div>
+    <div class="form-group" style="margin:0;align-self:flex-end;padding-bottom:1rem;">
+      <label style="display:flex;align-items:center;gap:0.4rem;font-weight:normal;cursor:pointer;">
+        <input type="checkbox" name="increment_cycles" value="1" checked>
+        Increment charge cycles
+      </label>
+    </div>
+    <div class="form-group" style="margin:0;flex:2;min-width:160px;">
+      <label>Notes (optional)</label>
+      <input type="text" name="notes" placeholder="e.g. trickle charge overnight">
+    </div>
+    <div style="padding-bottom:1rem;">
+      <button class="btn btn-primary" type="submit">Add</button>
+    </div>
+  </form>
+</div>
+
 <!-- Edit Details -->
 <div class="card">
   <h2>Edit Details</h2>

templates/dashboard.html

@@ -117,7 +117,7 @@
         <select id="bulk-device-select" name="device_id"
                 style="padding:0.25rem 0.5rem;font-size:0.85rem;border:1px solid #cbd5e1;border-radius:4px;">
           <option value="">— select device —</option>
-          {% for d in devices %}
+          {% for d in devices_with_slots %}
           <option value="{{ d.id }}">{{ d.name }} ({{ d.installed_count() }}/{{ d.battery_slots }})</option>
           {% endfor %}
         </select>
@@ -181,11 +181,8 @@
                 <select id="qas-{{ b.id }}"
                         style="padding:0.2rem 0.3rem;font-size:0.8rem;border:1px solid #cbd5e1;border-radius:4px;max-width:110px;vertical-align:middle;">
                   <option value="">— assign —</option>
-                  {% for d in devices %}
-                  <option value="{{ d.id }}"
-                    {% if d.installed_count() >= d.battery_slots %}disabled{% endif %}>
-                    {{ d.name }} ({{ d.installed_count() }}/{{ d.battery_slots }})
-                  </option>
+                  {% for d in devices_with_slots %}
+                  <option value="{{ d.id }}">{{ d.name }} ({{ d.installed_count() }}/{{ d.battery_slots }})</option>
                   {% endfor %}
                 </select>
                 <button type="button" class="btn btn-sm btn-primary"

templates/device_list.html

@@ -57,6 +57,12 @@
           </td>
           <td data-label="Actions" style="white-space:nowrap;">
             <a class="btn btn-sm btn-secondary" href="{{ url_for('device_detail', device_id=d.id) }}">View</a>
+            {% if d.installed_count() > 0 %}
+            <form class="inline" method="post" action="{{ url_for('device_unassign_all', device_id=d.id) }}"
+                  onsubmit="return confirm('Unassign all batteries from {{ d.name }}?')">
+              <button class="btn btn-sm btn-warning" type="submit">Unassign All</button>
+            </form>
+            {% endif %}
             <form class="inline" method="post" action="{{ url_for('device_delete', device_id=d.id) }}"
                   onsubmit="return confirm('Delete {{ d.name }}? All installed batteries will be unassigned.');">
               <button class="btn btn-sm btn-danger" type="submit">Delete</button>