Aero: heavier shared blur, and the composer field reads as a field

The composer's input was still a flat 60% white bar (the "clean, even tile"
from the earlier pass) on a panel that had rightly become translucent, so it
read as a white slab - "especially the part where you enter the prompt". It is
now the app's standard frosted tile plus one light veil: measured against the
same backdrop the field sits at 178,212,157 where the panel is 145,183,79 -
clearly a brighter field, still glass.

Translucent glass needs softness rather than opacity, so the shared backdrop
(background-blur.webp, the pre-blurred copy every Aero surface sits on) is
re-baked much softer - a 64x36 upscale - and every panel, card, chip and
button now shows the scene as an even frosted wash instead of white or mud.
?v=5 busts the asset.

Contrast scans stay clean (chat, library, study, settings across all three
themes, 0 findings) and all 15 suites pass. Version 0.6.4, SW v86.

README.md

@@ -1434,6 +1434,20 @@ Things I chose while building, with the reasoning:
     (measured: 268..1280 at a 1280 window) — a flat pane floating 40px inside the scene read as
     "cut off next to the sidebar".
 
+95. **Aero, second pass: a heavier shared blur, and a field that reads as a field.** Two follow-ups
+    on 94. The composer's input was still a flat 60% white bar (the "clean, even tile" from 91) on
+    a panel that had — rightly — become translucent, so it read as a white slab: "especially the
+    part where you enter the prompt". It is now the app's standard frosted tile plus one light
+    veil; measured against the same backdrop, the field sits at `178,212,157` where the panel is
+    `145,183,79`, so it is clearly a brighter *field* while the scene shows through. And because
+    translucent glass needs softness rather than opacity, the shared backdrop
+    (`background-blur.webp`, the pre-blurred copy every Aero surface sits on) was re-baked much
+    softer — a 64×36 upscale instead of the old half-res copy — so panels, cards, chips and
+    buttons all show the scene as an even frosted wash: nothing to read as a muddy patch, nothing
+    turned white. `?v=5` busts the asset. Library, chat, study and settings screens all scan at 0
+    below-minimum contrast findings in all three themes; phone touch still strips the bake
+    entirely (flat 32% glass, as in 93).
+
 94. **Aero glass goes back to glass (the "even wash" read as a white pane).** The uniform wash
     (`background-glass.webp`) from decisions 91/93 made the rail and the chat chrome nearly
     opaque: "why is the sidebar so white and non-translucent on the frutiger theme now? and the