feat: add instance segmentation postprocessing support

[CuriousDolphin]

This commit introduces:

• A new instance_postprocess function for handling instance segmentation outputs
• A get_postprocess_fn utility to dynamically select the appropriate postprocessing function
• Updated runtime classes to use the new postprocessing selection method
• Enhanced scale_detections to handle mask scaling for instance segmentation

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
runtime.py	170	108	36%	30, 38–39, 60–63, 65, 125–126, 128–131, 142, 146, 150, 160, 162–163, 165–167, 169, 172–174, 177, 180–182, 185, 188–189, 192–193, 196, 221–225, 227–228, 231–234, 236–237, 239, 243–246, 250–251, 253–255, 257–261, 263–264, 266–268, 272, 282–283, 293–297, 299, 301–302, 304–310, 314–317, 321–322, 324–325, 327–331, 333–334, 336–337, 339, 349–350
utils
vision.py	76	2	97%	55, 127
TOTAL	1036	153	85%

Tests	Skipped	Failures	Errors	Time
109	0 💤	0 ❌	0 🔥	7.864s ⏱️