v1.3.0 — NCBI fetch, IUPAC motifs, streaming, heatmap, 17 bug fixes

New: Fetch FASTA by NCBI accession (batch supported). IUPAC motif search (TATAWR, CANNTG). Streaming mode for files >10MB. Column heatmap
toggle. GC% sliding window plot. K-mer frequency table. Responsive toolbar. First/Last pagination.

Fixes: Large file stack overflow, heatmap on CSV columns, screenshot quality bars, light theme colors, HTML export all rows, highlight
dialog, race conditions.