fix(compose): default ODYSSEUS_TTS_CACHE_MAX_BYTES so compose stops warning (#6619) (#6645)

The three shipped compose files forwarded the variable bare, so every
`docker compose` command on a default .env printed "variable is not set".
Default it to the 500 MiB that .env.example documents, like the other
limits, and add a guard test that rejects any bare ${VAR} in compose files.

Fixes #6619

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Alexandre Teixeira <general@alexandreteixeira.dev>

tests/test_compose_env_defaults.py

@@ -0,0 +1,28 @@
+"""Every variable a shipped compose file forwards must carry a default.
+
+A bare ``${VAR}`` makes ``docker compose`` print "variable is not set" on every
+command for a default ``.env`` (#6619), which greets fresh installs with a
+warning that looks like a misconfiguration.
+"""
+
+import re
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[1]
+COMPOSE_FILES = sorted(ROOT.glob("docker-compose*.yml")) + sorted((ROOT / "docker").glob("*.yml"))
+
+# ${VAR} with no ``:-``/``-``/``:?``/``?`` modifier.
+BARE_VAR = re.compile(r"\$\{([A-Za-z_][A-Za-z0-9_]*)\}")
+
+
+@pytest.mark.parametrize("path", COMPOSE_FILES, ids=lambda p: p.relative_to(ROOT).as_posix())
+def test_compose_variables_have_defaults(path):
+    bare = [
+        f"{path.name}:{lineno}: ${{{name}}}"
+        for lineno, line in enumerate(path.read_text(encoding="utf-8").splitlines(), 1)
+        if not line.lstrip().startswith("#")
+        for name in BARE_VAR.findall(line)
+    ]
+    assert not bare, "compose variables without a default:\n" + "\n".join(bare)