exploring gather results in a more intuitive/friendly way

[ctb]

see https://github.com/ctb/2025-explore-sourmash-gather. Example output:

% ~/2025-explore-sourmash-gather/explore-gather.py display SRR4420318.k51.csv
** displaying gather results for given CSVs: n=3, t=0.01

Query: SRR4420318 (90.7% assigned in 981 total matches; 3 shown)
  1: GCF_000001405.40 human (Homo sapiens) - 83.8% (83.8%) - 1.6 Gbp
  2: GCA_900184025.1 Amynthas corticis - 3.4% (87.2%) - 180.0 kbp
  3: GCA_029289425.3 pygmy chimpanzee (Pan... - 1.0% (88.2%) - 0.8 Gbp
  ... (978 matches not shown)

this could become a plugin, ofc.