ST_ENC_C1: per-coeff Compress_du via comp_decomp_sync (mode 0) then
LSB-first byte packing into ct_bram. 5-phase micro-seq reads u[cp_poly]
from bank_se (rel K+poly), feeds the compressor (1-cyc pipe), appends du
bits to cp_buf, and drains whole bytes. Each poly = 256*du bits (whole
bytes) so the bit buffer empties at every poly boundary.
ST_ENC_U now advances to ST_ENC_C1 (was ST_DONE).
TB: verify_e5 compares ct_bram[0..c1_bytes-1] to the KAT.ct prefix via
the dbg_ct tap. run_enc.sh: encaps TB runner (compiles comp_decomp_sync
which the KeyGen tcl omits).
Verified K=2/3/4 c1 == KAT.ct prefix (640/960/1408 B; K=4 du=11
cross-byte path), K=2 cases 0-2.
FallenSigh
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