feat: expose exact Function column freshness (#4958)

## Problem

Function-backed columns need an exact `fresh`, `stale`,
`never_computed`, and
`failed` partition for the table version a caller is reading. The
existing
error listing is capped, and composing it with job and schema listings
cannot
prove which rows currently failed.

## Behavior

- Adds a strict freshness reader beside the existing permissive planner.
It
  distinguishes an absent certificate from legacy evidence that omits
  failures, and from a current certificate carrying failure coverage.
- Extends the immutable freshness sidecar with per-fragment known and
failed
  row bitmaps. Partial or `WHERE` publications cover only observed rows;
  untouched rows stay unknown. Deleted rows do not block classification.
- Adds failure-aware whole-fragment and row-repair writers. A rejected
older
attempt cannot overwrite failure evidence already recorded for a newer
input
  signature.
- Adds `column_status`, `column_statuses`, and `wait_fresh` to Python
and the
  corresponding Node methods. The client calls the server's exact status
endpoint, validates the four-way partition and one-version guarantee,
and
preserves the complete Function version, last-job, and automatic-refresh
  metadata.
- Adds an MDX-commented draft usage section to the Enterprise
computed-column
refresh guide, covering Python, Rust, and TypeScript and remaining
hidden
  until the server integration ships.
- Sends `column`, `branch`, and exact `version` selectors to the status
route.
A pinned handle rejects a nonempty response from any other table
version;
  latest handles keep the existing read-freshness headers.
- Retries `wait_fresh` only for HTTP 503 with
`function_column_status_finalization_pending`. Existing failed rows
remain
  visible and do not keep the wait pending; other errors propagate.
- Models the shared scheduler projection, including `up_to_date`, real
`blocked` states, their reason, failure streak, and effective cooldown.

## Validation

This is the SDK side of ENT-3563. Sophon's failure-coverage publication
and
status endpoint are a separate integration; deployed end-to-end and
whole-ticket
acceptance remain pending.

- Rust: 9 exact freshness/status tests passed, plus 1 exact
latest-handle
  freshness-header test. The pinned transport test was extended with a
wrong-version response and rerun at `ebd6649a` (1 passed). Coverage
includes untouched partial rows,
  selected-row failure clearing, cross-generation evidence, typed and
non-retried errors, `up_to_date`, blocked scheduler fields, and
exact-version
  requests.
- Python: 2 native PyO3 remote-transport tests passed together,
including
typed retry; one local facade test reaches the existing unsupported
boundary.
- Node: the NAPI addon built successfully, TypeScript and Biome passed,
and the
selected native remote-transport test passed 1/0, including
exact-version
  selection and blocked scheduler metadata.
- `cargo fmt`, `git diff --check`, Ruff format/lint, Python compile,
Biome, and
  TypeScript checks passed.

Validation is mapped by the relevant unchanged source rather than
treated as one
final-head run: the nine Rust tests ran at `e4d51fc8`, the latest-header
and Python
remote tests at `31e68b7d`, the local Python test and Node build at
`6f213584`, and
the final TypeScript/Jest delta at `4f2d5c27`. The final product tree
excludes those five private EC2 runner files and adds
six generated TypeDoc files plus one hidden draft usage section in the
computed-column refresh guide. The Node delta corrected a private
TypeScript
command and reused the unchanged native addon.

python/src/lib.rs

@@ -16,9 +16,10 @@ use query::{FTSQuery, HybridQuery, Query, VectorQuery};
 use session::Session;
 use table::{
     AddColumnsResult, AddResult, AlterColumnsResult, DeleteResult, DropColumnsResult, FtsToken,
-    FunctionErrorFragment, FunctionErrorRecord, FunctionErrors, MergeResult, PyBlobFile,
-    RTEWriteSpec, RefreshColumnResult, RefreshMaterializedViewResult, Table,
-    UpdateFieldMetadataResult, UpdateResult,
+    FunctionColumnAutoRefreshStatus, FunctionColumnLastRefreshJob, FunctionColumnStatus,
+    FunctionColumnVersionStatus, FunctionErrorFragment, FunctionErrorRecord, FunctionErrors,
+    MergeResult, PyBlobFile, RTEWriteSpec, RefreshColumnResult, RefreshMaterializedViewResult,
+    Table, UpdateFieldMetadataResult, UpdateResult,
 };
 
 pub mod arrow;
@@ -117,6 +118,10 @@ pub fn _lancedb(py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<FunctionErrors>()?;
     m.add_class::<FunctionErrorRecord>()?;
     m.add_class::<FunctionErrorFragment>()?;
+    m.add_class::<FunctionColumnStatus>()?;
+    m.add_class::<FunctionColumnVersionStatus>()?;
+    m.add_class::<FunctionColumnLastRefreshJob>()?;
+    m.add_class::<FunctionColumnAutoRefreshStatus>()?;
     m.add_class::<RefreshMaterializedViewResult>()?;
     m.add_class::<AlterColumnsResult>()?;
     m.add_class::<UpdateFieldMetadataResult>()?;