feat: Kokoro 82M TTS engine + voice profile type system

Add Kokoro-82M as a new TTS engine — 82M params, CPU realtime, 8 languages,
Apache 2.0. Unlike cloning engines, Kokoro uses pre-built voice styles, which
required a new profile type system to support non-cloning engines cleanly.

Kokoro engine:
- New kokoro_backend.py implementing TTSBackend protocol
- 50 built-in voices across en/es/fr/hi/it/pt/ja/zh
- KPipeline API with language-aware G2P routing via misaki
- PyInstaller bundling for misaki, language_tags, espeakng_loader, en_core_web_sm

Voice profile type system:
- New voice_type column: 'cloned' | 'preset' | 'designed' (future)
- Preset profiles store engine + voice ID instead of audio samples
- default_engine field on profiles — auto-selects engine on profile pick
- Create Voice dialog: toggle between 'Clone from audio' and 'Built-in voice'
- Edit dialog shows preset voice info instead of sample list for preset profiles
- Engine selector locks to preset engine when preset profile is selected
- Profile grid filters by engine — shows Kokoro voices when Kokoro selected
- Custom empty state when no preset profiles exist for selected engine

Bug fixes:
- Fix relative audio paths in DB causing 404s in production builds
- config.set_data_dir() now resolves to absolute paths
- Startup migration converts existing relative paths to absolute

Also updates PROJECT_STATUS.md and tts-engines.mdx developer guide.

app/src/lib/hooks/useGenerationForm.ts

@@ -17,7 +17,7 @@ const generationSchema = z.object({
   seed: z.number().int().optional(),
   modelSize: z.enum(['1.7B', '0.6B', '1B', '3B']).optional(),
   instruct: z.string().max(500).optional(),
-  engine: z.enum(['qwen', 'luxtts', 'chatterbox', 'chatterbox_turbo', 'tada']).optional(),
+  engine: z.enum(['qwen', 'luxtts', 'chatterbox', 'chatterbox_turbo', 'tada', 'kokoro']).optional(),
 });
 
 export type GenerationFormValues = z.infer<typeof generationSchema>;
@@ -83,7 +83,9 @@ export function useGenerationForm(options: UseGenerationFormOptions = {}) {
                 ? data.modelSize === '3B'
                   ? 'tada-3b-ml'
                   : 'tada-1b'
-                : `qwen-tts-${data.modelSize}`;
+                : engine === 'kokoro'
+                  ? 'kokoro'
+                  : `qwen-tts-${data.modelSize}`;
       const displayName =
         engine === 'luxtts'
           ? 'LuxTTS'
@@ -95,9 +97,11 @@ export function useGenerationForm(options: UseGenerationFormOptions = {}) {
                 ? data.modelSize === '3B'
                   ? 'TADA 3B Multilingual'
                   : 'TADA 1B'
-                : data.modelSize === '1.7B'
-                  ? 'Qwen TTS 1.7B'
-                  : 'Qwen TTS 0.6B';
+                : engine === 'kokoro'
+                  ? 'Kokoro 82M'
+                  : data.modelSize === '1.7B'
+                    ? 'Qwen TTS 1.7B'
+                    : 'Qwen TTS 0.6B';
 
       // Check if model needs downloading
       try {