Use dependency groups for Python SDK tooling (#27538)

## Summary

`just fmt` previously used `uv run --with ruff` to make Ruff available.
Because `--with` creates an ephemeral overlay outside the project
lockfile, uv periodically re-resolved Ruff (by default every 10 minutes)
instead of using the version recorded in `uv.lock`.

Move the Python SDK tooling dependencies from the published `dev` extra
into `format`, `test`, and composed `dev` dependency groups. The
formatter now selects only the locked `format` group, contributor and CI
setup explicitly sync the `dev` group, and CI and release commands reuse
that environment with `--frozen --no-sync`. The scripts formatter also
uses its project's locked Ruff dependency instead of an ephemeral
overlay.

Validated the Python 3.12 SDK suite (119 passed, 38 skipped) and the
repository formatter.

scripts/format.py

@@ -37,17 +37,15 @@ class FormatterResult:
 def formatter_groups(*, check: bool) -> tuple[FormatterGroup, ...]:
     just_args = ["just", "--unstable", "--fmt"]
     cargo_args = ["cargo", "fmt", "--", "--config", "imports_granularity=Item"]
-    # Use an unpinned overlay so Ruff is available without syncing project
-    # dependencies. Each `--project` still retains its local configuration context.
+    # Each `--project` retains its local dependency and Ruff configuration context.
     sdk_uv_run_args = [
         "uv",
         "run",
         "--frozen",
         "--project",
         "sdk/python",
-        "--no-sync",
-        "--with",
-        "ruff",
+        "--only-group",
+        "format",
     ]
     scripts_uv_run_args = [
         "uv",
@@ -55,9 +53,6 @@ def formatter_groups(*, check: bool) -> tuple[FormatterGroup, ...]:
         "--frozen",
         "--project",
         "scripts",
-        "--no-sync",
-        "--with",
-        "ruff",
     ]
     sdk_format_args = [
         *sdk_uv_run_args,