engines: import f5-tts + kokoro + tortoise sidecars into the tree

The python FastAPI sidecars have lived ad-hoc at /mnt/cache/appdata/
<engine>/build/ on Lucy without version control. Bringing them into
the skald repo so the engine code travels with the cross-engine
routing it depends on.

This commit lands the VANILLA version of each engine on main:

  engines/f5-tts/    SWivid F5-TTS (CC-BY-NC weights flagged)
  engines/kokoro/    hexgrad Kokoro-82M (Apache 2.0 top to bottom)
  engines/tortoise/  neonbjb Tortoise-TTS (Apache 2.0 top to bottom)

Engine-specific kludges (question doubling, GPU coordination,
pause-duration tuning) get layered on engine/* branches per the
README. Main stays the safe-to-read baseline.

engines/tortoise/compose.yml

@@ -0,0 +1,43 @@
+# Tortoise-TTS stack on Lucy. Audiobook-quality engine with 25+
+# named voices (no cloning). Apache 2.0 top to bottom.
+#
+# Slow: ~10x kokoro wall clock at 'standard' preset. Worth it for
+# the quality bar. Cobb's call 2026-05-14: "use higgs (now tortoise)
+# and we will only let it use the full gpu for runs" — translated:
+# runs are batched, slow is acceptable.
+#
+# Co-resides with kokoro on the 2070 Super since tortoise is ~5GB
+# and kokoro is ~1GB (8GB total). If OOM hits during a render,
+# we'll add a coordination layer to pause kokoro first.
+name: tortoise
+
+services:
+  tortoise:
+    image: lucy-registry:5000/tortoise:0.1
+    container_name: tortoise
+    restart: unless-stopped
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              count: all
+              capabilities: [gpu]
+    ports:
+      - "192.168.0.5:7795:7860"
+      - "127.0.0.1:7795:7860"
+    volumes:
+      - /mnt/cache/appdata/tortoise/hf-cache:/cache/hf
+      - /mnt/cache/appdata/tortoise/models:/cache/tortoise-models
+      # Shared audio dir with f5/kokoro so skald serves all engines'
+      # outputs through the same /audio route.
+      - /mnt/cache/appdata/f5-tts/audio:/audio
+    environment:
+      HF_HOME: /cache/hf
+      HF_HUB_DISABLE_TELEMETRY: "1"
+      TORTOISE_MODELS_DIR: /cache/tortoise-models
+    labels:
+      org.sulkta.domain: "sulkta"
+      org.sulkta.owner: "cobb"
+      org.sulkta.managed-by: "compose"
+      org.sulkta.role: "tortoise-tts"