fix(BA-6887): reference the real from_status/to_status columns in kernel history conditions

KernelSchedulingHistoryConditions.by_from_phase/by_to_phase referenced
KernelSchedulingHistoryRow.from_phase and .to_phase. Those columns exist
under different names: the table defines from_status and to_status, so
either factory would have raised AttributeError once its condition was
evaluated.

The names drifted from an incomplete rename. BA-3061 first created
kernel_scheduling_history with from_phase/to_phase columns. BA-3062 then
renamed them to from_status/to_status by editing that not-yet-released
migration in place, but the query conditions added in the same change kept
the old names. The stale reference later survived the move from
repositories/scheduling_history/options.py into this module (BA-5127).

Two things kept it hidden: nothing calls either factory yet, so the closure
was never evaluated; and the cast() wrapper kept the bad attribute access
away from the type checker.

Rename to by_from_status/by_to_status to match both the column names and the
equivalent session factories, and drop the now-unneeded cast(). Renaming
outright is safe as there are no callers.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jopemachine

changes/12857.fix.md

@@ -0,0 +1 @@
+Point the kernel scheduling-history query conditions at the `from_status` / `to_status` columns the table actually defines, instead of the pre-rename `from_phase` / `to_phase` names.

src/ai/backend/manager/models/scheduling_history/conditions.py

@@ -422,22 +422,16 @@ def inner() -> sa.sql.expression.ColumnElement[bool]:
         return inner
 
     @staticmethod
-    def by_from_phase(phase: KernelSchedulingPhase) -> QueryCondition:
+    def by_from_status(phase: KernelSchedulingPhase) -> QueryCondition:
         def inner() -> sa.sql.expression.ColumnElement[bool]:
-            return cast(
-                sa.sql.expression.ColumnElement[bool],
-                KernelSchedulingHistoryRow.from_phase == str(phase),
-            )
+            return KernelSchedulingHistoryRow.from_status == str(phase)
 
         return inner
 
     @staticmethod
-    def by_to_phase(phase: KernelSchedulingPhase) -> QueryCondition:
+    def by_to_status(phase: KernelSchedulingPhase) -> QueryCondition:
         def inner() -> sa.sql.expression.ColumnElement[bool]:
-            return cast(
-                sa.sql.expression.ColumnElement[bool],
-                KernelSchedulingHistoryRow.to_phase == str(phase),
-            )
+            return KernelSchedulingHistoryRow.to_status == str(phase)
 
         return inner