stacks/index-tts: revert git-lfs build attempt; document the LFS

budget hazard + media-CDN workaround

Tried adding git-lfs install + git lfs pull to the build to get
real example WAVs into the image — failed with:

    Error downloading object: examples/emo_hate.wav: Smudge error:
    batch response: This repository exceeded its LFS budget. The
    account responsible for the budget should increase it to
    restore access.

The index-tts org's LFS bandwidth quota is exhausted upstream and
out of our control. Reverting the Dockerfile change. The examples
aren't needed for the wrapper to work; emotion_text and
emotion_vector are sufficient for end-to-end testing without any
WAV file at all.

For users who want the bundled example clips as starter audio,
README now documents the media-CDN URL trick — same LFS objects
served via a different code path that doesn't count against the
LFS API budget. INDEX_TTS_TAG stays at v1.

stacks/index-tts/.env.example

@@ -6,10 +6,8 @@
 INDEX_TTS_SHA=830f6f8f94a51fea23ab1d639027a86200075a4e
 
 # Local image tag — bump when you change build context (Dockerfile,
-# app.py, entrypoint.sh) to force a fresh layer build. v2 = git-lfs
-# added so the example WAVs in /opt/index-tts/examples/ come down as
-# real audio (v1 left them as LFS pointer stubs).
-INDEX_TTS_TAG=v2
+# app.py, entrypoint.sh) to force a fresh layer build.
+INDEX_TTS_TAG=v1
 
 # ── network ──────────────────────────────────────────────────────────
 # Host port. Container listens on 8000 internally.