Remove --soft-weight and --local-snr spot-finder options

Both were opt-in adaptive-spot refinements that did not help. Soft per-spot
weighting was index-rate neutral across the battery (re-ranking only bites when
spots exceed the max-spot cap, which weak serial data does not reach). The
local-SNR gate was neutral on index rate and degraded merged CC1/2 on flooded
XFEL data. Drops the flags, ApplyWeights/FilterByLocalSNR, the per-spot weight
field, and the by-weight FilterSpotsByCount branch (now strongest-first only).
--adaptive-spots itself is unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

common/DiffractionSpot.cpp

@@ -85,7 +85,6 @@ std::optional<SpotToSave> DiffractionSpot::Export(const DiffractionGeometry &geo
         .lattice = -1,
         .image = image_num,
         .d_A = d,
-        .weight = weight,
         .ice_ring = false,
         .indexed = false
     };