feat: Editable safety settings in SettingsModal

Backend:
- New POST /api/image-gen/config endpoint to update image generation config
  in-memory (applies immediately, resets on server restart)
- Accepts: model, safety_harassment, safety_hate_speech,
  safety_sexually_explicit, safety_dangerous

Frontend:
- SettingsModal safety filters are now editable dropdowns (no longer disabled)
- Model selection is also editable
- Added 'Save Changes' button with visual feedback:
  * Green 'Settings saved!' on success
  * Red 'Failed to save' on error
  * Disabled when no changes made
- Tracks edited state vs. saved state
- Note: changes apply immediately but reset on server restart
  (set .env for persistence)

Fixed TypeScript issues:
- getConfigValue() properly typed to return string only
- Proper union type for config keys excluding has_api_key

frontend/src/components/SettingsModal.tsx

@@ -35,14 +35,19 @@ const SAFETY_OPTIONS = [
 export default function SettingsModal({ isOpen, onClose, onClearWaveforms, onDeleteAll, clipCount }: Props) {
   const [confirmDelete, setConfirmDelete] = useState(false)
   const [loading, setLoading] = useState(false)
+  const [saving, setSaving] = useState(false)
   const [imageGenModels, setImageGenModels] = useState<ImageGenModel[]>([])
   const [imageGenConfig, setImageGenConfig] = useState<ImageGenConfig | null>(null)
+  const [editedConfig, setEditedConfig] = useState<Partial<ImageGenConfig>>({})
   const [showImageGenSettings, setShowImageGenSettings] = useState(false)
+  const [saveMessage, setSaveMessage] = useState('')
 
   useEffect(() => {
     if (isOpen) {
       fetchImageGenModels()
       fetchImageGenConfig()
+      setEditedConfig({})
+      setSaveMessage('')
     }
   }, [isOpen])
 
@@ -95,6 +100,42 @@ export default function SettingsModal({ isOpen, onClose, onClearWaveforms, onDel
     }
   }
 
+  const handleSaveImageGenConfig = async () => {
+    if (!editedConfig || Object.keys(editedConfig).length === 0) return
+    setSaving(true)
+    try {
+      const res = await fetch('/api/image-gen/config', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(editedConfig),
+      })
+      if (res.ok) {
+        setSaveMessage('Settings saved!')
+        setImageGenConfig(prev => prev ? { ...prev, ...editedConfig } : prev)
+        setEditedConfig({})
+        setTimeout(() => setSaveMessage(''), 2000)
+      } else {
+        setSaveMessage('Failed to save')
+      }
+    } catch (e) {
+      setSaveMessage('Failed to save')
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  const updateEditedConfig = (key: string, value: string) => {
+    setEditedConfig(prev => ({ ...prev, [key]: value }))
+    setSaveMessage('')
+  }
+
+  const getConfigValue = (key: 'model' | 'safety_harassment' | 'safety_hate_speech' | 'safety_sexually_explicit' | 'safety_dangerous'): string => {
+    const val = editedConfig[key] ?? imageGenConfig?.[key]
+    return typeof val === 'string' ? val : 'BLOCK_ONLY_HIGH'
+  }
+
+  const hasChanges = Object.keys(editedConfig).length > 0
+
   return (
     <div className="fixed inset-0 z-50 flex items-center justify-center">
       {/* Backdrop */}
@@ -150,12 +191,8 @@ export default function SettingsModal({ isOpen, onClose, onClearWaveforms, onDel
                   <label className="block text-xs text-lyria-muted mb-1.5">Model</label>
                   <select
                     className="w-full bg-black/30 border border-white/10 rounded-md px-3 py-2 text-sm text-white focus:outline-none focus:border-lyria-accent"
-                    value={imageGenConfig?.model || 'gemini-3.1-flash-image-preview'}
-                    onChange={(e) => {
-                      // This would need a backend endpoint to update config
-                      // For now, it's read-only from .env
-                      console.log('Model selection changed:', e.target.value)
-                    }}
+                    value={getConfigValue('model')}
+                    onChange={(e) => updateEditedConfig('model', e.target.value)}
                   >
                     {imageGenModels.map((model) => (
                       <option key={model.id} value={model.id}>
@@ -163,9 +200,6 @@ export default function SettingsModal({ isOpen, onClose, onClearWaveforms, onDel
                       </option>
                     ))}
                   </select>
-                  <p className="text-xs text-lyria-muted/60 mt-1">
-                    Configure via IMAGE_GEN_MODEL in .env
-                  </p>
                 </div>
 
                 {/* API Key Status */}
@@ -189,8 +223,8 @@ export default function SettingsModal({ isOpen, onClose, onClearWaveforms, onDel
                       <label className="block text-xs text-lyria-muted mb-1">{label}</label>
                       <select
                         className="w-full bg-black/30 border border-white/10 rounded-md px-3 py-1.5 text-sm text-white focus:outline-none focus:border-lyria-accent"
-                        value={imageGenConfig?.[key as keyof ImageGenConfig] as string || 'BLOCK_ONLY_HIGH'}
-                        disabled
+                        value={getConfigValue(key as 'safety_harassment' | 'safety_hate_speech' | 'safety_sexually_explicit' | 'safety_dangerous')}
+                        onChange={(e) => updateEditedConfig(key, e.target.value)}
                       >
                         {SAFETY_OPTIONS.map((opt) => (
                           <option key={opt.value} value={opt.value}>{opt.label}</option>
@@ -198,10 +232,26 @@ export default function SettingsModal({ isOpen, onClose, onClearWaveforms, onDel
                       </select>
                     </div>
                   ))}
-                  <p className="text-xs text-lyria-muted/60">
-                    Configure via IMAGE_GEN_SAFETY_* in .env
-                  </p>
                 </div>
+
+                {/* Save Button */}
+                <div className="flex items-center gap-3 pt-2">
+                  <button
+                    onClick={handleSaveImageGenConfig}
+                    disabled={!hasChanges || saving}
+                    className="px-4 py-2 text-sm font-medium rounded-md transition-colors disabled:opacity-50 bg-lyria-accent text-black hover:bg-lyria-accent/90"
+                  >
+                    {saving ? 'Saving...' : 'Save Changes'}
+                  </button>
+                  {saveMessage && (
+                    <span className={`text-xs ${saveMessage.includes('Failed') ? 'text-red-400' : 'text-green-400'}`}>
+                      {saveMessage}
+                    </span>
+                  )}
+                </div>
+                <p className="text-xs text-lyria-muted/60">
+                  Changes apply immediately but reset on server restart. Set .env for persistence.
+                </p>
               </div>
             )}
           </div>