fix(themes): P1 palette retunes from the design audit + gated subtext floor (item 28b)

The audit's P1s, fixed at the palette level (items 25/27 previously
patched the consumers around these):
- summer-day: surface was the TEXT color (slate #5c6a72 on cream) and
  subtext was the BASE (ratio 1.0, invisible) — now a raised cream
  surface #efe7d0 and a slate-teal subtext #6e828a in the theme's
  family.
- flexoki-light: surface/overlay/muted were all the text black and
  subtext the paper — retuned to canonical upstream Flexoki tones
  (ui #E6E4D9, #B7B5AC, tx-2 #6F6E69, base-500 #878580).
- miasma: pure-black surface under a #222 base → raised #2e2e2e.
- kanagawa: surface was sumiInk0 (darker than the bg) → upstream's
  raised sumiInk4 #2a2a37.
check-theme-contrast.py gains the adopted rule: subtext on base >= 3.0
(all 21 themes pass), so the invisible-secondary-text class cannot
ship again. Model note in the backlog: `overlay` is a mid-tone role
(catppuccin semantics), not a third bg tier.

Verified: V0 + checks.theme-contrast green (21x3); re-audit shows all
four P1 findings gone; a scratch downstream with summer-day active
builds and the new surface hex lands in the rendered ghostty config.
Remains: V3 four-theme eyeball (HARDWARE-QUEUE) and 28b's P2 floors +
exemption list.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent/BACKLOG.md

@@ -50,7 +50,13 @@ Bernardo has offered image-expert models for designed graphics
 needs artwork must STOP and ask ("say the word") instead of shipping
 programmer-art.
 Slices: (a) ✓ the audit (2026-07-05, iteration #31 — findings below);
-(b) palette-level fixes + the extended contrast/harmony checker;
+(b) palette-level fixes + the extended contrast/harmony checker —
+P1s ✓ shipped 2026-07-05 (iteration #32): summer-day + flexoki-light
+subtext/surface/overlay/muted retuned (flexoki to its canonical
+upstream tones), miasma + kanagawa surfaces raised (kanagawa to
+sumiInk4); `subtext/base ≥ 3` now GATED in check-theme-contrast.py
+(all 21 pass). Remaining (b): the P2 floors below + the per-theme
+exemption-list mechanism, then re-audit;
 (c) per-surface polish slices;
 (d) the whole-swap themes brought to the same bar. Visual work is
 V3-bound by nature — screenshots are the review artifact, hardware
@@ -58,15 +64,15 @@ confirms.
 
 **Audit findings (slice a — `tools/audit-theme-design.py` over all 21
 palettes + visual pass over previews; identity-aware curation):**
-- **P1 · invisible-secondary-text palettes:** summer-day and
-  flexoki-light have `subtext == base` (contrast 1.0 — literally
-  invisible) and `text == surface`. Items 25/27 fixed the *consumers*
-  (swaync/bar stopped using them); the palettes are still traps — any
-  new surface consuming subtext/surface re-trips. Fix the palettes:
-  real mid-tone subtext, raised surface.
-- **P1 · inverted bg stacks:** miasma's surface is #000000 under a
-  much lighter base; kanagawa's surface (L .14) sits below base
-  (L .24). "Raised" surfaces render sunken/black. Retune.
+- ~~P1 · invisible-secondary-text palettes~~ ✓ fixed iteration #32
+  (summer-day subtext #6e828a, surface #efe7d0; flexoki-light to
+  canonical Flexoki: surface #E6E4D9, overlay #B7B5AC, subtext
+  #6F6E69, muted #878580). Gate added.
+- ~~P1 · inverted bg stacks~~ ✓ fixed iteration #32 (miasma surface
+  #2e2e2e; kanagawa surface #2a2a37 = upstream sumiInk4). Note
+  learned: in this palette model `overlay` is a MID-TONE
+  (borders/dim, catppuccin semantics), not a third bg tier — the
+  dark-theme overlay==muted pattern is intentional.
 - **P2 · muted floor:** muted-on-base < 2.0 on gruvbox (1.27),
   everforest (1.55), lumon (1.68), nord (1.69), white (1.82), latte
   (1.91), retro-82 (1.93) — dimmed workspaces/inactive items barely