feat: expose Function call concurrency limits (#4956)

## Summary

Adds an optional `max_concurrency` setting to Function registration and
explicit refresh:

- A registered Function version can define the default maximum number of
user-code calls in flight for one logical execution.
- A refresh can override that default for that execution only.
- The value must be a positive `u32` and is independent from
`resource_budget`; it is not an account-wide quota.
- Omitting the option preserves the previous request payload. Local
embedded refreshes reject this Enterprise-only option.

Rust, Python sync/async, PyO3, and the existing Node refresh surface
forward the option. Node has no Function registration surface today, so
no registration API is added there. The generated TypeDoc pages are
included for the new public option.

## Validation

The native-tested source covers Function version decoding, registration
validation and serialization, the Flight SQL registration ticket and
returned version, remote refresh forwarding, local rejection, and Node's
numeric boundary before conversion. Exact stage results are Rust `1+3`
plus four remote cases at `1` each; Python `14/1/49/24`; Node `57`
remote and `1` local rejection. Ruff, standard repository Pyright, and
Biome passed.

The tested Python extension was
`21aa256a970f4a16ea8253d68401d0fc573d946412e8752155dfcad63f30654d`; the
tested Node addon and generated native declaration were
`f6089f861981f96f8ce0f6dbef43de0907b9eeb4b63e84cdd5da14e00d6cbd30` and
`4c4ceb205824075d706897c726c215dcf839880c757f0d0582d24cec5f938416`. The
final 24-file diff preserves the 22 tested
product/test/fixture/source-doc blobs and adds only two generated
TypeDoc pages.

python/src/table.rs

@@ -48,6 +48,7 @@ mod scannable;
 struct RefreshColumnArgs {
     where_clause: Option<String>,
     batch_size: Option<i64>,
+    max_concurrency: Option<u32>,
     publication_interval_rows: Option<i64>,
     resource_budget: Option<FunctionWorkerResourceBudget>,
     gpu_class: Option<String>,
@@ -73,6 +74,31 @@ fn positive_count<T: TryFrom<i64>>(value: Option<i64>, name: &str) -> PyResult<O
         .transpose()
 }
 
+fn positive_u32_integer(value: Option<&Bound<'_, PyAny>>, name: &str) -> PyResult<Option<u32>> {
+    let Some(value) = value else {
+        return Ok(None);
+    };
+    if value.is_none() || value.is_instance_of::<PyBool>() {
+        return Err(PyValueError::new_err(format!(
+            "{name} must be an integer between 1 and 4294967295"
+        )));
+    }
+    let parsed = value.extract::<i64>().map_err(|_| {
+        PyValueError::new_err(format!(
+            "{name} must be an integer between 1 and 4294967295"
+        ))
+    })?;
+    u32::try_from(parsed)
+        .ok()
+        .filter(|parsed| *parsed > 0)
+        .map(Some)
+        .ok_or_else(|| {
+            PyValueError::new_err(format!(
+                "{name} must be an integer between 1 and 4294967295"
+            ))
+        })
+}
+
 fn resource_budget_integer(
     value: &Bound<'_, PyAny>,
     name: &str,
@@ -136,6 +162,7 @@ fn refresh_column_options(args: RefreshColumnArgs) -> PyResult<RefreshColumnOpti
     let RefreshColumnArgs {
         where_clause,
         batch_size,
+        max_concurrency,
         publication_interval_rows,
         resource_budget,
         gpu_class,
@@ -179,6 +206,7 @@ fn refresh_column_options(args: RefreshColumnArgs) -> PyResult<RefreshColumnOpti
         .map(usize::try_from)
         .transpose()
         .map_err(|_| PyValueError::new_err("batch_size must be greater than zero"))?;
+    options.max_concurrency = max_concurrency;
     options.publication_interval_rows =
         positive_count(publication_interval_rows, "publication_interval_rows")?;
     options.resource_budget = resource_budget;
@@ -2282,13 +2310,14 @@ impl Table {
         })
     }
 
-    #[pyo3(signature = (column, *, r#where=None, batch_size=None, publication_interval_rows=None, resource_budget=None, gpu_class=None, gpu_count=None, retry_policy=None, error_policy=None, max_failed_fraction=None, max_failed_rows=None, row_timeout_seconds=None, init_timeout_seconds=None, num_workers=None, max_executor_processes_per_worker=None))]
+    #[pyo3(signature = (column, *, r#where=None, batch_size=None, max_concurrency=None, publication_interval_rows=None, resource_budget=None, gpu_class=None, gpu_count=None, retry_policy=None, error_policy=None, max_failed_fraction=None, max_failed_rows=None, row_timeout_seconds=None, init_timeout_seconds=None, num_workers=None, max_executor_processes_per_worker=None))]
     #[allow(clippy::too_many_arguments)]
     pub fn refresh_column<'py>(
         self_: PyRef<'py, Self>,
         column: String,
         r#where: Option<String>,
         batch_size: Option<i64>,
+        max_concurrency: Option<Bound<'py, PyAny>>,
         publication_interval_rows: Option<i64>,
         resource_budget: Option<Bound<'py, PyDict>>,
         gpu_class: Option<String>,
@@ -2305,6 +2334,7 @@ impl Table {
         let options = refresh_column_options(RefreshColumnArgs {
             where_clause: r#where,
             batch_size,
+            max_concurrency: positive_u32_integer(max_concurrency.as_ref(), "max_concurrency")?,
             publication_interval_rows,
             resource_budget: parse_resource_budget(resource_budget.as_ref())?,
             gpu_class,
@@ -2328,13 +2358,14 @@ impl Table {
         })
     }
 
-    #[pyo3(signature = (column, *, r#where=None, batch_size=None, publication_interval_rows=None, resource_budget=None, gpu_class=None, gpu_count=None, retry_policy=None, error_policy=None, max_failed_fraction=None, max_failed_rows=None, row_timeout_seconds=None, init_timeout_seconds=None, num_workers=None, max_executor_processes_per_worker=None))]
+    #[pyo3(signature = (column, *, r#where=None, batch_size=None, max_concurrency=None, publication_interval_rows=None, resource_budget=None, gpu_class=None, gpu_count=None, retry_policy=None, error_policy=None, max_failed_fraction=None, max_failed_rows=None, row_timeout_seconds=None, init_timeout_seconds=None, num_workers=None, max_executor_processes_per_worker=None))]
     #[allow(clippy::too_many_arguments)]
     pub fn refresh_column_async<'py>(
         self_: PyRef<'py, Self>,
         column: String,
         r#where: Option<String>,
         batch_size: Option<i64>,
+        max_concurrency: Option<Bound<'py, PyAny>>,
         publication_interval_rows: Option<i64>,
         resource_budget: Option<Bound<'py, PyDict>>,
         gpu_class: Option<String>,
@@ -2351,6 +2382,7 @@ impl Table {
         let options = refresh_column_options(RefreshColumnArgs {
             where_clause: r#where,
             batch_size,
+            max_concurrency: positive_u32_integer(max_concurrency.as_ref(), "max_concurrency")?,
             publication_interval_rows,
             resource_budget: parse_resource_budget(resource_budget.as_ref())?,
             gpu_class,