Wrong result in TiKV of year comparsion

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

```sql
DROP TABLE IF EXISTS t0;
CREATE TABLE t0(c0 YEAR NOT NULL );
CREATE INDEX i0 ON t0(c0);
REPLACE INTO t0(c0) VALUES ('1935'), ('1982');
ALTER TABLE t0 SET TIFLASH REPLICA 1;
SELECT /*+ READ_FROM_STORAGE(tikv[t0]) */ t0.c0 FROM t0 WHERE 0.025 <= t0.c0;
SELECT /*+ READ_FROM_STORAGE(tiflash[t0]) */ t0.c0 FROM t0 WHERE 0.025 <= t0.c0;
```

### 2. What did you expect to see? (Required)

see the following case: TiKV and Tiflash return different result

### 3. What did you see instead (Required)

```sql
mysql> SELECT /*+ READ_FROM_STORAGE(tiflash[t0]) */ t0.c0 FROM t0 WHERE 0.025 <= t0.c0;
+------+
| c0 |
+------+
| 1935 |
| 1982 |
+------+
2 rows in set (0.04 sec)

mysql> SELECT /*+ READ_FROM_STORAGE(tikv[t0]) */ t0.c0 FROM t0 WHERE 0.025 <= t0.c0;
Empty set (0.04 sec)
```

### 4. What is your TiDB version? (Required)

8.5.0

Start by running the provided SQL reproduction on TiKV and TiFlash with TiDB 8.5.0, then trace how the YEAR comparison is evaluated in each storage path. Done means both storage hints return consistent, correct results for the reproduction case, with regression coverage for the discrepancy.

Written by the indexing model from the issue text.