Replace the two-script Python pipeline (analysis report + Elixir-source
emitter) with a single `scripts/recalibrate.py` that fits per-band
weights from PSKR spot density (VHF/UHF) and contacts↔HRRR correlations
(microwave), writing `priv/algo/band_weights.json` as a machine-readable
artifact. A new Elixir BandWeights module loads this JSON once via
`:persistent_term` cache; BandConfig.weights/1 consults it before falling
back to in-source overrides or global defaults. The script never touches
Elixir source — recalibration is now `python3 scripts/recalibrate.py`
followed by an app restart.
