fix(themes): fidelity hierarchy nits + #52 residual ANSI (#67, #68)

#67 hierarchy: nord subtext dimmer than text; tokyo-night btop Night
blues; ethereal surface raise + muted darker than overlay; retro-82
surface raised; ristretto subtext distinct + btop main_bg align;
flexoki-light distinct bright-black; gruvbox overlay/subtext ladder
(no rename).

#68 residual ANSI: vantablack ansi[8]=muted; osaka-jade ansi[3]=warn.

Verified: python3 tools/check-theme-contrast.py themes/ → 24×7 all pass.

themes/osaka-jade.json

@@ -43,7 +43,7 @@
     "#23372B",
     "#FF5345",
     "#549e6a",
-    "#459451",
+    "#E5C736",
     "#509475",
     "#D2689C",
     "#2DD5B7",