refactor: clean up code quality issues

- backend.py: replace walrus-then-overwrite pattern with plain assignments
  in _to_catalog_db_tuple
- backend.py: getattr(self, '_http', None) is not None -> hasattr(self, '_http')
- backend.py: add explanatory comments to the silent pass in
  _resolve_database_connection_id and the no-op _register_in_memory_table
- http.py: replace magic HTTP status integers with http.HTTPStatus constants
- http.py: replace range(len(columns)) index loop with direct field iteration
- types.py: cache m.group(2) to avoid calling it twice
- Remove managed.py (single-constant module); inline 'public' directly at
  the two call sites in backend.py and http.py

Author: eddietejeda

src/ibis_hotdata/backend.py

@@ -43,7 +43,6 @@
 from ibis.backends.sql import SQLBackend
 
 from ibis_hotdata.http import HotdataAPIError, HotdataClient
-from ibis_hotdata.managed import DEFAULT_SCHEMA
 from ibis_hotdata.types import dtype_from_hotdata_sql_type
 
 _INFORMATION_SCHEMA_PAGE_SIZE = 500
@@ -203,7 +202,7 @@ def do_connect(
         )
 
     def disconnect(self) -> None:
-        if getattr(self, "_http", None) is not None:
+        if hasattr(self, "_http"):
             self._http.close()
 
     # --- hierarchy ---------------------------------------------------------
@@ -253,10 +252,12 @@ def _to_catalog_db_tuple(self, table_loc: sge.Table):
         """Use the compiler SQL dialect when stringifying qualifiers (backend name is not a dialect)."""
 
         dialect = self.dialect
-        if (sg_cat := table_loc.args["catalog"]) is not None:
+        sg_cat = table_loc.args["catalog"]
+        if sg_cat is not None:
             sg_cat.args["quoted"] = False
             sg_cat = sg_cat.sql(dialect=dialect)
-        if (sg_db := table_loc.args["db"]) is not None:
+        sg_db = table_loc.args["db"]
+        if sg_db is not None:
             sg_db.args["quoted"] = False
             sg_db = sg_db.sql(dialect=dialect)
 
@@ -429,7 +430,7 @@ def _resolve_database_connection_id(self) -> str | None:
                 db = self._http.get_database(self._database_id)
                 self._database_connection_id = db.get("default_connection_id")
             except HotdataAPIError:
-                pass
+                pass  # best-effort: if the lookup fails, callers fall back to the catalog name
         return self._database_connection_id
 
     # --- schema / sql execution --------------------------------------------
@@ -575,7 +576,7 @@ def create_database(
         /,
         *,
         catalog: str | None = None,
-        schema: str = DEFAULT_SCHEMA,
+        schema: str = "public",
         tables: Sequence[str] | None = None,
         force: bool = False,
     ) -> None:
@@ -722,7 +723,7 @@ def drop_table(
             raise _ibis_err_from_hotdata(exc) from exc
 
     def _register_in_memory_table(self, _op: ops.InMemoryTable) -> None:
-        return
+        pass  # Hotdata has no local in-memory table concept; Ibis calls this hook before execute
 
     @cached_property
     def version(self) -> str:

src/ibis_hotdata/http.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import http
 import io
 import json
 import time
@@ -30,8 +31,6 @@
 from hotdata.models.database_default_table_decl import DatabaseDefaultTableDecl
 from hotdata.models.load_managed_table_request import LoadManagedTableRequest
 
-from ibis_hotdata.managed import DEFAULT_SCHEMA
-
 T = TypeVar("T")
 
 # Matches Hotdata / runtimedb ``GET /v1/results/{{id}}`` Arrow responses.
@@ -197,7 +196,7 @@ def create_managed_database(
         self,
         description: str | None = None,
         *,
-        schema: str = DEFAULT_SCHEMA,
+        schema: str = "public",
         tables: Sequence[str] = (),
     ) -> dict[str, Any]:
         """POST ``/v1/databases`` — creates a managed database with an auto-provisioned default catalog."""
@@ -264,27 +263,27 @@ def _poll_result_arrow(
             status = raw.status
             ctype = (raw.headers.get("Content-Type") or "").split(";")[0].strip().lower()
 
-            if status == 200 and ctype == APPLICATION_ARROW_STREAM.lower():
+            if status == http.HTTPStatus.OK and ctype == APPLICATION_ARROW_STREAM.lower():
                 table = _ipc_stream_bytes_to_table(body)
                 return self._arrow_payload_from_table(table, result_id=result_id)
 
-            if status == 202:
+            if status == http.HTTPStatus.ACCEPTED:
                 _sleep_until(deadline, poll_interval_s)
                 continue
 
-            if status == 409:
+            if status == http.HTTPStatus.CONFLICT:
                 d = _json_utf8(body) if body else {}
                 raise HotdataAPIError(
                     d.get("error_message") or "Result failed",
-                    status_code=409,
+                    status_code=http.HTTPStatus.CONFLICT,
                     body=d,
                 )
 
-            if status == 404:
+            if status == http.HTTPStatus.NOT_FOUND:
                 d = _json_utf8(body) if body else {}
                 raise HotdataAPIError(
                     d.get("detail") or f"Result {result_id!r} not found",
-                    status_code=404,
+                    status_code=http.HTTPStatus.NOT_FOUND,
                     body=d,
                 )
 
@@ -304,7 +303,7 @@ def _arrow_payload_from_table(
     ) -> dict[str, Any]:
         sch = table.schema
         columns = sch.names
-        nullable = [sch.field(i).nullable for i in range(len(columns))]
+        nullable = [field.nullable for field in sch]
         return {
             "format": "arrow",
             "pa_table": table,

src/ibis_hotdata/managed.py

@@ -80,7 +80,8 @@ def _pa_type_from_arrow_str(raw: str) -> pa.DataType | None:
     m = _TIMESTAMP_RE.match(s)
     if m:
         unit = m.group(1).lower()
-        tz: str | None = m.group(2).strip() if m.group(2) else None
+        tz_raw = m.group(2)
+        tz: str | None = tz_raw.strip() if tz_raw else None
         try:
             return pa.timestamp(unit, tz=tz)
         except Exception: