config(char-rp-gguf): Deckard reasoning seat to full 256K (GDN-hybrid KV cheap)

Deckard (Qwen3.5-27B) native ctx = 262144; GDN-hybrid arch (16 KV-caching layers) makes KV
cheap (8.7G q8_0 @ 256K vs Magidonia 10.9G @ 128K/40 dense layers). Bumped 40960 -> 262144;
GPU0 ~4G free (static -> stable). Canonical RP-reasoning samplers pending dvalin (card has
only generic base-Qwen3.5 profiles); empirical temp1.0/top_p0.95/top_k40/min_p0.05+DRY0.8 live.

stacks/char-rp-gguf/compose.yaml

@@ -124,8 +124,8 @@ services:
       - "${CHARRP_REASONING_CTX:-40960}"
       - --flash-attn
       - on
-      # Deckard = Qwen3.5-27B (native ctx large); 40960 is a sane reasoning-seat cap. q8_0 KV
-      # verified coherent; flip to f16 in .env if a future model shows gibberish.
+      # Deckard = Qwen3.5-27B GDN-hybrid (16 KV-caching layers → KV cheap); native ctx 262144
+      # (256K, no YaRN). Full 256K @ q8_0 KV ≈ 8.5G. q8_0 verified coherent; f16 in .env if gibberish.
       - --cache-type-k
       - ${CHARRP_REASONING_KV_TYPE:-q8_0}
       - --cache-type-v