fix: Allow duration multiplied w/ primitive to propagate in IR schema

[mcrumiller]

Closes #21389.

Right now, duration * primitive does not propagate the dtype and results in a schema error if the resulting expression is used afterwards, despite it being a valid operation.

from datetime import datetime, timedelta
import polars as pl
from polars import col

df = pl.DataFrame({
    "ts": [datetime(2025, 1, 1)],
    "dur": [timedelta(days=1)],
})

df.select(col("dur") * 2)              # OK
df.select(2 * col("dur"))              # OK
df.select(col("ts") + col("dur"))      # OK
df.select(col("ts") + 2 * col("dur"))  # OK
df.select(col("ts") + col("dur") * 2)  # ERROR!!!
# polars.exceptions.InvalidOperationError: + not allowed on datetime[μs] and unknown

After fix:

>>> df.select(col("ts") + col("dur") * 2)
shape: (1, 1)
┌─────────────────────┐
│ ts                  │
│ ---                 │
│ datetime[μs]        │
╞═════════════════════╡
│ 2025-01-03 00:00:00 │
└─────────────────────┘

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.96%. Comparing base (3719977) to head (1780991).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-plan/src/plans/aexpr/schema.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #21394      +/-   ##
==========================================
+ Coverage   79.89%   79.96%   +0.07%     
==========================================
  Files        1597     1597              
  Lines      228951   228954       +3     
  Branches     2618     2618              
==========================================
+ Hits       182915   183082     +167     
+ Misses      45437    45273     -164     
  Partials      599      599              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.