fix(tools): wrap bare scalars in single-element list for array-typed args

Open-weight models (DeepSeek, Qwen, GLM) sometimes emit tool calls like
`{"urls": "https://a.com"}` when the tool schema declares
`type: array`.  The call was JSON-valid but semantically wrong, and
`coerce_tool_args` would pass the bare string through — the tool then
failed with a confusing type error.

`coerce_tool_args` now wraps non-list, non-null values in a
single-element list when the schema declares `array`.  Strings still go
through `_coerce_value` first so JSON-encoded arrays
(`'["a","b"]'`) parse correctly and nullable `"null"` still
becomes `None`.  `None` itself is preserved — tools with sensible
defaults already handle it, and we don't want to silently mask a
deliberate null.

Salvaged from #19652 (NikolayGusev-astra) — the broader validate-then-
repair layer had several issues (duplicated existing coercion,
mis-classified `old_string` as a path field, prepended non-JSON
prefixes to tool results that break downstream JSON parsing, hardcoded
offset/limit defaults unsuitable for non-read_file tools).  The one
genuinely new capability is wrapping bare scalars, which is implemented
here directly inside the existing coercion path.

Co-authored-by: Nikolay Gusev <ngusev@astralinux.ru>

scripts/release.py

@@ -48,6 +48,7 @@ AUTHOR_MAP = {
     "127238744+teknium1@users.noreply.github.com": "teknium1",
     "159539633+MottledShadow@users.noreply.github.com": "MottledShadow",
     "aludwin+gh@gmail.com": "adamludwin",
+    "ngusev@astralinux.ru": "NikolayGusev-astra",
     "2093036+exiao@users.noreply.github.com": "exiao",
     "rylen.anil@gmail.com": "rylena",
     "godnanijatin@gmail.com": "jatingodnani",