Add environment settings to Settings tab

Add environment configuration section in SettingsTab component with:
- Current environment type display and dropdown for standalone apps
- Disabled state with badge for linked apps (environment locked)
- Warning section for linked apps with unlink button
- Settings row styling for consistent layout

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/ApplicationDetail.jsx

@@ -1722,6 +1722,16 @@ const LogsTab = ({ app }) => {
 const SettingsTab = ({ app, onUpdate }) => {
     const navigate = useNavigate();
     const [deleting, setDeleting] = useState(false);
+    const [environmentType, setEnvironmentType] = useState(app.environment_type || 'standalone');
+    const [savingEnvironment, setSavingEnvironment] = useState(false);
+    const [unlinking, setUnlinking] = useState(false);
+
+    const envLabels = {
+        standalone: 'Standalone',
+        production: 'Production',
+        development: 'Development',
+        staging: 'Staging'
+    };
 
     async function handleDelete() {
         if (!confirm(`Delete ${app.name}? This action cannot be undone.`)) return;
@@ -1737,10 +1747,95 @@ const SettingsTab = ({ app, onUpdate }) => {
         }
     }
 
+    async function handleEnvironmentChange(newType) {
+        if (newType === app.environment_type) return;
+
+        setSavingEnvironment(true);
+        try {
+            await api.updateAppEnvironment(app.id, newType);
+            setEnvironmentType(newType);
+            onUpdate();
+        } catch (err) {
+            console.error('Failed to update environment:', err);
+            setEnvironmentType(app.environment_type || 'standalone');
+        } finally {
+            setSavingEnvironment(false);
+        }
+    }
+
+    async function handleUnlink() {
+        if (!confirm(`Unlink ${app.name} from its linked application? Both apps will become standalone.`)) return;
+
+        setUnlinking(true);
+        try {
+            await api.unlinkApp(app.id);
+            onUpdate();
+        } catch (err) {
+            console.error('Failed to unlink app:', err);
+        } finally {
+            setUnlinking(false);
+        }
+    }
+
     return (
         <div>
             <h3>Application Settings</h3>
 
+            {/* Environment Configuration */}
+            <div className="card settings-section">
+                <h4>Environment Configuration</h4>
+                <div className="settings-row">
+                    <div className="settings-label">
+                        <span>Environment Type</span>
+                        <span className="settings-hint">
+                            {app.has_linked_app
+                                ? 'This app is linked. Unlink to change environment type.'
+                                : 'Set how this application is used in your workflow.'}
+                        </span>
+                    </div>
+                    <div className="settings-control">
+                        {app.has_linked_app ? (
+                            <span className={`env-badge env-${app.environment_type}`}>
+                                {envLabels[app.environment_type] || app.environment_type}
+                            </span>
+                        ) : (
+                            <select
+                                value={environmentType}
+                                onChange={(e) => handleEnvironmentChange(e.target.value)}
+                                disabled={savingEnvironment}
+                                className="settings-select"
+                            >
+                                <option value="standalone">Standalone</option>
+                                <option value="development">Development</option>
+                                <option value="staging">Staging</option>
+                                <option value="production">Production</option>
+                            </select>
+                        )}
+                        {savingEnvironment && <span className="settings-saving">Saving...</span>}
+                    </div>
+                </div>
+
+                {app.has_linked_app && (
+                    <div className="settings-row settings-linked-warning">
+                        <div className="settings-label">
+                            <span>Linked Application</span>
+                            <span className="settings-hint">
+                                This app is linked to another application. Unlinking will reset both apps to standalone mode.
+                            </span>
+                        </div>
+                        <div className="settings-control">
+                            <button
+                                className="btn btn-secondary"
+                                onClick={handleUnlink}
+                                disabled={unlinking}
+                            >
+                                {unlinking ? 'Unlinking...' : 'Unlink Application'}
+                            </button>
+                        </div>
+                    </div>
+                )}
+            </div>
+
             <div className="card danger-zone">
                 <h4>Danger Zone</h4>
                 <p>Once you delete an application, there is no going back.</p>

frontend/src/styles/pages/_settings.less

@@ -813,3 +813,79 @@
     color: @text-secondary;
     font-size: @font-size-sm;
 }
+
+// Settings Row (for app settings tab)
+.settings-row {
+    display: flex;
+    justify-content: space-between;
+    align-items: flex-start;
+    padding: @space-4;
+    background: @bg-hover;
+    border-radius: @radius-md;
+    gap: @space-4;
+
+    &:not(:last-child) {
+        margin-bottom: @space-3;
+    }
+
+    &.settings-linked-warning {
+        background: fade(@warning, 10%);
+        border: 1px solid fade(@warning, 20%);
+    }
+}
+
+.settings-label {
+    flex: 1;
+
+    > span:first-child {
+        display: block;
+        font-weight: @font-weight-medium;
+        color: @text-primary;
+        margin-bottom: @space-1;
+    }
+
+    .settings-hint {
+        display: block;
+        font-size: @font-size-xs;
+        color: @text-tertiary;
+    }
+}
+
+.settings-control {
+    display: flex;
+    align-items: center;
+    gap: @space-2;
+    flex-shrink: 0;
+}
+
+.settings-select {
+    min-width: 160px;
+    padding: @space-2 @space-3;
+    background: @bg-card;
+    border: 1px solid @border-subtle;
+    border-radius: @radius-md;
+    color: @text-primary;
+    font-size: @font-size-sm;
+    cursor: pointer;
+    transition: border-color @transition-fast;
+
+    &:hover {
+        border-color: @border-default;
+    }
+
+    &:focus {
+        outline: none;
+        border-color: @accent-primary;
+    }
+
+    &:disabled {
+        opacity: 0.6;
+        cursor: not-allowed;
+    }
+}
+
+.settings-saving {
+    font-size: @font-size-xs;
+    color: @text-tertiary;
+    font-style: italic;
+}