v0.23.0:0 - local / fine-tuned model support

Add models that live as a directory on a Spark (e.g. LoRA-merged fine-tunes),
not just Hugging Face repos.

- ModelDef gains local_path; a model must set exactly one of repo / local_path.
  The validator also enforces the local-path whitelist and that any
  --chat-template lives inside local_path (only that dir is mounted).
- build_launch_command bind-mounts the dir into the vLLM container at the SAME
  host==container path via the launch script's VLLM_SPARK_EXTRA_DOCKER_ARGS hook,
  then `vllm serve <dir>`. No launch-cluster.sh change (verified the upstream
  expands that var unquoted; contract noted in runbook.md).
- shellsafe.validate_local_path: absolute path, charset whitelist, no '.'/'..'.
- POST /api/models validates the full entry via ModelDef before persisting, so a
  bad entry can't be written and then break catalog load; _merge_overrides skips
  an invalid override entry instead of failing the whole catalog.
- disk.py size-probes a local path with du; disk-delete refused for local models.
- UI: "+ Add local model" dialog, `local` badge, path shown instead of an HF
  link, delete button hidden for local models.
- Tests: local launch + injection round-trip, chat-template location, traversal,
  exactly-one-source, _merge_overrides skip-invalid (94 pass). Reviewer-agent
  pass; findings addressed.

image/app/shellsafe.py

@@ -28,6 +28,12 @@ _IMAGE_RE = re.compile(r"^[A-Za-z0-9][A-Za-z0-9._:/@-]*$")
 # Docker container / volume name (Docker's own rule).
 _CONTAINER_RE = re.compile(r"^[A-Za-z0-9][A-Za-z0-9_.-]*$")
 
+# Absolute filesystem path to a local model directory on a Spark. Conservative
+# charset (letters, digits, and safe path punctuation) with a required leading
+# '/', so it carries no shell metacharacters and no whitespace. Traversal ('.'
+# and '..' segments) is rejected separately in validate_local_path.
+_LOCAL_PATH_RE = re.compile(r"^/[A-Za-z0-9._+/-]+$")
+
 
 def validate_repo(repo: str) -> str:
     """Return `repo` if it is a well-formed 'org/name'; else raise ValueError."""
@@ -50,6 +56,25 @@ def validate_container(name: str) -> str:
     return name
 
 
+def validate_local_path(path: str) -> str:
+    """Return `path` if it is a safe absolute model directory path; else ValueError.
+
+    For locally fine-tuned models served by directory (not an HF repo). Requires
+    an absolute path, a metacharacter-free charset, and no '.'/'..' segments so a
+    caller cannot traverse out of an intended models directory. The `quote_arg`
+    sink still quotes it in depth — this is the boundary check.
+    """
+    p = path or ""
+    if len(p) > 512 or not _LOCAL_PATH_RE.fullmatch(p):
+        raise ValueError(
+            f"invalid local model path (expected an absolute path, no spaces or "
+            f"shell metacharacters): {path!r}"
+        )
+    if any(seg in (".", "..") for seg in p.split("/")):
+        raise ValueError(f"local model path must not contain '.' or '..' segments: {path!r}")
+    return p
+
+
 def quote_arg(value: object) -> str:
     """shlex.quote a single token for safe embedding in a shell command string."""
     return shlex.quote(str(value))