Release v3.0.0

[joeljose]

Bumps VERSION and __version__ to 3.0.0 and moves the Unreleased CHANGELOG entries under [3.0.0] - 2026-09-28.

Why a major release:

• Output differs from 2.0.0 for the same settings: filter centring (CPU FFT temporal filter is one frame out of step with the direct-convolution and GPU paths (even-length windows) #29), rounding (Audit follow-ups: output rounding bias, non-finite -k/-w, unvalidated filter names, dtcwt vs NumPy 2, float64 GPU input, doc slips #43), the NaN fix (CPU path: exact-zero wavelet coefficients produce NaN, which shows up as black regions in the output #22), and float32 on the CPU (CPU path peaks at 8.26 GiB on face.mp4 (README says ~1.2 GB); estimate_memory() is never called and underestimates #26).
• The library API changed: load_video returns uint8, magnify_motions returns float32 with new keyword arguments, and scripts need a __main__ guard when jobs > 1.
• The Docker build and run changed: no build args, a fixed user, and --gpu in the GPU image's entrypoint.

These are listed as BREAKING in the CHANGELOG and in the README's new "Breaking Changes → v3.0.0" section. The README intro now summarises v3.0.0.

After merge: tag the merge commit v3.0.0 (annotated) and push the tag. Docker images pick up the new VERSION label on their next build.