update webgl nuke effects (#3984)

## Description:

Reworks the visual look of nuked tiles to read uniformly green (no more
brown/black bleed-through), and moves the ember "particle" effect out of
the border passes — where it lived as a storage-sharing hack — into the
fallout system where it belongs.

## What changed visually

- **Fresh fallout**: bright uniform bloom with a hint of flickering
green particles dampened on fresh tiles, ramping up as heat decays
(`particleFreshScale` controls the fresh-tile dampening).
- **Stale fallout**: dark-green ground (was near-black charcoal), with
full-strength flickering particles in dark-green ↔ light-green.
- **Particles**: per-tile flicker is now de-synced (each tile pulses at
its own rate, 0.4×–1.6× base speed) so the eye can't lock onto a global
rhythm.
- **No more brown/black pixels** in fallout zones. Two root causes were
fixed:
- The territory pass now renders stale-nuke ground for **all** fallout
tiles, not just unowned ones — so an owned player's color can't show
through where the bloom is dim/transparent.
- The ember stamp (which fully replaced tile color with orange) is gone;
particle render is now additive and color-tuned green.

## Architecture cleanup

The ember effect was conceptually fallout-domain, but lived in
`BorderComputePass` (writing intensity into `borderTex.g`) and
`BorderStampPass` (stamping orange dots), just because the border pass
already had an RGBA8 texture with a free G channel. Two consumers read
from it (`BorderStampPass`, `FalloutLightPass`), and the per-tile
flicker math used no border data at all.

This PR relocates the math inline into the two passes that actually need
it (`FalloutBloomPass.extract.frag.glsl` and
`FalloutLightPass.fallout-light.frag.glsl`), drops the ember code from
both border passes, and renames `mapOverlay.ember*` →
`falloutBloom.particle*` so the settings live with their pass.

Side benefits:
- **Animation correctness**: the old setup only updated ember intensity
when `BorderComputePass`'s dirty flag flipped (highlight change,
relations update, etc.), so the supposed flicker was actually a frozen
snapshot between border events. The new inline path runs every frame as
intended.
- **Slightly cheaper per-frame compute**: removed a per-dirty-event
full-map writeback to `borderTex.g`; added a few cheap ALU ops (1 sin +
2 hashes) per fallout tile in shaders that were already running. Same
texture memory.

## Other small changes

- Renamed `mapOverlay.charcoal*` → `mapOverlay.staleNuke*` (charcoal was
a misnomer now that the ground is green).
- Added `staleNukeR/G/B` for the ground color (was hardcoded grey).
- `intensityHot` bumped 0.6 → 1.8 for a brighter fresh-nuke glow.
- Raised `railroad.railMinZoom` 2 → 4 and `railDetailZoom` 4 → 6 so
rails pop in later (separate small commit).

<img width="354" height="371" alt="Screenshot 2026-05-22 at 10 37 34 AM"
src="https://github.com/user-attachments/assets/03b46c45-c617-41b3-b3e4-9934f064bfe1"
/>
<img width="335" height="358" alt="Screenshot 2026-05-22 at 10 37 43 AM"
src="https://github.com/user-attachments/assets/af370b19-8f22-4694-9859-1ad52aa755a7"
/>
<img width="651" height="613" alt="Screenshot 2026-05-22 at 10 38 09 AM"
src="https://github.com/user-attachments/assets/e06e5101-8529-49f6-b29a-ce0563eb52d6"
/>


## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/client/render/gl/render-settings.json

@@ -23,7 +23,7 @@
     "contrastHiHot": 0,
     "metaFreq": 0.02,
     "intensityCold": 0.15,
-    "intensityHot": 0.6,
+    "intensityHot": 1.8,
     "metaInfluenceCold": 1,
     "metaInfluenceHot": 0,
     "opacityFadeEnd": 1,
@@ -31,7 +31,18 @@
     "bloomG": 0.8196078431372549,
     "bloomB": 0,
     "bloomCoverage": 1.1,
-    "heatDecayPerTick": 1
+    "heatDecayPerTick": 1,
+    "particleColorDarkR": 0.05,
+    "particleColorDarkG": 0.4,
+    "particleColorDarkB": 0.05,
+    "particleColorBrightR": 0.2,
+    "particleColorBrightG": 1,
+    "particleColorBrightB": 0.2,
+    "particleThresholdUnowned": 0.85,
+    "particleThresholdOwned": 0.875,
+    "particleFlickerSpeed": 0.2,
+    "particleStrength": 1,
+    "particleFreshScale": 0.2
   },
   "dayNight": {
     "mode": "light",
@@ -53,19 +64,12 @@
   "mapOverlay": {
     "trailAlpha": 0.588,
     "defenseCheckerDarken": 0.7,
-    "charcoalBase": 0,
-    "charcoalVariation": 0.05,
-    "charcoalAlpha": 0.87,
-    "emberThresholdUnowned": 0.85,
-    "emberThresholdOwned": 0.875,
-    "emberFlickerSpeed": 0.12,
-    "emberColorDarkR": 0.6,
-    "emberColorDarkG": 0.15,
-    "emberColorDarkB": 0,
-    "emberColorBrightR": 1,
-    "emberColorBrightG": 0.5,
-    "emberColorBrightB": 0.05,
-    "emberStrengthUnowned": 0.5,
+    "staleNukeBase": 0,
+    "staleNukeVariation": 0.05,
+    "staleNukeAlpha": 1,
+    "staleNukeR": 0.05,
+    "staleNukeG": 0.55,
+    "staleNukeB": 0.07,
     "highlightBrighten": 0.25,
     "highlightFillBrighten": 0.15,
     "highlightThicken": 2,