fix(python): surface typed remote resource errors (#4789)

## Summary

- Parse structured `error_code` and `resource` fields from remote HTTP
error bodies and carry them through Rust/PyO3.
- Add `SecretNotFoundError`, `FunctionNotFoundError`,
`NamespaceNotFoundError`, and `AlreadyExistsError` as `HttpError`
subclasses.
- Expose `error_code`, `resource_kind`, `resource_name`, and
`namespace_path` on HTTP exceptions while preserving `status_code`,
`request_id`, and existing `except HttpError` handlers.
- Do not retry structured domain errors that would otherwise become
`RetryError` (notably `already_exists` on 409).

Older servers that do not provide the structured fields continue to
raise a plain `HttpError`.

## Compatibility

This consumes the stable resource error contract added in
lancedb/sophon#9516 (merge commit `35858561b3`). The existing
`TableNotFoundError` behavior is unchanged.

Part of ENT-3373.

docs/src/python/python.md

@@ -748,10 +748,45 @@ so the fetch APIs cannot read their bytes yet.
 
 ## Exceptions
 
+Remote HTTP responses with structured resource details raise a subclass of
+`HttpError`. Older servers that omit those details raise plain `HttpError`, so
+`except HttpError` remains a compatible catch-all:
+
+```python
+from lancedb.remote.errors import (
+    AlreadyExistsError,
+    FunctionNotFoundError,
+    HttpError,
+    NamespaceNotFoundError,
+    SecretNotFoundError,
+)
+
+try:
+    db.describe_namespace(["analytics"])
+except (SecretNotFoundError, FunctionNotFoundError, NamespaceNotFoundError) as error:
+    print(error.error_code, error.resource_kind, error.resource_name)
+except AlreadyExistsError as error:
+    print("resource already exists:", error.resource_name)
+except HttpError as error:
+    print("request failed:", error.request_id, error.status_code)
+```
+
+Secret and function lifecycle APIs currently use Flight SQL and may still raise
+`RuntimeError`. The typed subclasses cover HTTP failures, including dependency
+errors during column refresh.
+
 ::: lancedb.remote.errors.HttpError
 
 ::: lancedb.remote.errors.TableNotFoundError
 
+::: lancedb.remote.errors.SecretNotFoundError
+
+::: lancedb.remote.errors.FunctionNotFoundError
+
+::: lancedb.remote.errors.NamespaceNotFoundError
+
+::: lancedb.remote.errors.AlreadyExistsError
+
 ::: lancedb.exceptions.MissingValueError
 
 ::: lancedb.exceptions.MissingColumnError