fix: handle scalar input with bytes=True in Colormap.__call__

[abhi-0203]

Summary

Fixes Colormap.__call__ raising ValueError when called with a scalar input and bytes=True.

Problem

When bytes=True, the LUT is converted to uint8 before indexing. For scalar input, the result is a 4-element uint8 array (e.g. [32, 144, 140, 255]), which is then passed to Color(). But Color() (via parse_rgba) only accepts:

• integer arrays of length 3 (RGB)
• float arrays of length 3 or 4

A uint8 array of length 4 doesn't match either condition, raising ValueError: Invalid color array.

cmap(0.5, bytes=True)  # raises ValueError

Fix

When bytes=True and the input is scalar, normalize the uint8 RGBA values back to [0, 1] float range before constructing Color(). The quantization to 8-bit is preserved — Color(rgba / 255) gives #20908C vs #21918C in float mode, showing the bytes=True effect.

Test results

>>> cmap(0.5, bytes=True)
#20908C  # was ValueError before
>>> cmap(0.5)
#21918C  # unchanged
>>> cmap(np.array([0.5]), bytes=True)
[[ 32 144 140 255]]  # unchanged

Closes #153

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.67%. Comparing base (02fa073) to head (03fa2ff).

Files with missing lines	Patch %	Lines
src/cmap/_colormap.py	80.00%	1 Missing ⚠️

❌ Your patch check has failed because the patch coverage (80.00%) is below the target coverage (85.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #154      +/-   ##
==========================================
- Coverage   95.71%   95.67%   -0.04%     
==========================================
  Files         168      168              
  Lines        2192     2196       +4     
==========================================
+ Hits         2098     2101       +3     
- Misses         94       95       +1     

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