feat: Add temporal support

[hoxbro]

Still very much WIP... needs to be cleaned up.

Playground code used:

import numpy as np
import pandas as pd

import datashader as ds

# TODO: NaT support, unit check, bounds check (already set), tz support, verify it is 64
n = 1000
dts = pd.date_range("2026-01-01", periods=n, freq="h")  # .astype(int) works
dts = pd.date_range("2026-01-01", periods=n, freq="h", tz="UTC")  # .astype(int) works

#dts = dts.astype("datetime64[ms]")
a = pd.timedelta_range(start='1s', periods=n)

# Create a DataFrame with some values
df = pd.DataFrame(
    {
        "x": np.random.choice(dts, size=n),
        "y": np.random.choice(a, size=n),
        "value": np.random.randn(n),
    }
)
df.iloc[0, 0] = pd.NaT

# Create canvas
canvas = ds.Canvas(
    plot_width=800,
    plot_height=400,
    x_range=(dts[1], dts[-1]),
   # x_axis_type = "datetime",
   # y_axis_type = "datetime",
)

# Aggregate the data by summing the 'value' column
agg = canvas.points(df, "x", "y", agg=ds.mean("value"))

# Convert to image
import datashader.transfer_functions as tf

tf.shade(agg)

[codspeed-hq]

Merging this PR will improve performance by 28.07%

⚡ 1 improved benchmark
✅ 42 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	test_layout[forceatlas2_layout]	58.5 ms	45.6 ms	+28.07%

---

_{Comparing feat_temporal_support (4b21c4b) with main (77d4174)}

[codecov]

Codecov Report

❌ Patch coverage is 77.10843% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.37%. Comparing base (77d4174) to head (4b21c4b).

Files with missing lines	Patch %	Lines
datashader/core.py	66.66%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1475      +/-   ##
==========================================
- Coverage   88.42%   88.37%   -0.06%     
==========================================
  Files          96       96              
  Lines       19226    19289      +63     
==========================================
+ Hits        17001    17046      +45     
- Misses       2225     2243      +18     

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