Add pressure dial, wave spawn telegraphs, and readability pass

- Bigger gore-red Minis (r10->14, sprite 32->48) with regenerated art
- Wider, walkable doorways: clear passage for open, teeth only when locked
- 500ms spawn telegraph so wave spawns no longer blindside the player
- Item stickiness ramps 10%/owned item (cap 50%) instead of flat 50%
- Title-screen Pressure Dial (-5..+5) tunes rise/relief; score x live pressure
- Vitals HUD: two-row hearts, half-container outlines, half-heart shield pips
- Readable 8-page field manual (bigger panel + fonts, implants split)
- HUD opacity slider in pause menu (boss bar + toasts stay opaque)
- Scrap Feed now has diminishing returns like Thick Hide
- Docs, cache-bust v37, and smoke coverage for all of the above

docs/perks.md

@@ -70,7 +70,7 @@ XP comes from gems dropped by kills, room clears, and bosses, scaled by your `xp
 | **Carrion Sense** | +8% pickup radius and pull speed | `magnet ×1.08`, `magnetPull ×1.08` *(note: pull speed is not currently wired into pickup movement — the radius half works)* |
 | **Scavenger** | +4% drop luck | `luck +0.04` |
 | **Bloodrush** | +5% XP gain, bonus crystal chance | `xpMul ×1.05` |
-| **Scrap Feed** | 5% less ammo consumed | `ammoEff ×1.05` |
+| **Scrap Feed** | 5% less ammo (diminishing) | `ammoEff +0.05` per stack — saving fraction = rating/(1+rating), so each extra stack helps less (like Thick Hide) |
 
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