Rebalance Doomsday Clock: late-game stalemate-breaker (10min grace + wave squeeze), slower troop drain, gentler-but-steeper warship attrition (#4518)

Resolves #<add your approved & assigned issue number>

## Description:

Rebalances the Doomsday Clock so it acts as a **late-game
stalemate-breaker** rather than an early-game culler, softens how fast
it removes troops and warships, and makes the HUD countdown clearer.

**Clock schedule (all presets):**
- A flat **10-minute grace** at 0% required share — the early game is
decided by combat, not the clock.
- Then a 6-wave squeeze at accelerating levels (4 / 9 / 16 / 26 / 40 /
55%) with short pauses, reaching the final 55% at each preset's cap:
**45 / 35 / 25 / 15 min** for slow / normal / fast / veryfast.
- `WaveSchedule` `rampSeconds`/`pauseSeconds` are now **per-wave
arrays**, so the curve can be shaped (gentle early, steeper late)
instead of one uniform ramp. `requiredBasisPoints` and the HUD companion
`doomsdayClockWaveState` walk the per-wave segments in lockstep.

**Troop drain:** warn window `10s → 30s`, drain eased (`2%→5%` over
`90s`), so a caught side takes ~2 minutes to wipe instead of ~1.

**Warship attrition:** warships get their own gentler start plus a
**convex** decay curve — a ship caught when its side is first doomed
lasts about as long as troops, but the rate ramps up steeply so a side
at full attrition still loses its fleet in ~2s. Adds a `curveExponent`
argument to `doomsdayClockDrain` (1 = linear, used for troops; higher =
convex, used for ships).

**Determinism:** the drain curve is **integer-only** (fixed-point power,
no floats), so the floored per-tick loss is bit-identical on every
client in the lockstep sim. The linear troop path keeps its exact
existing integer form; only the convex warship path is reshaped.

**HUD countdown clarity:** the clock readout now shows a live countdown
in both states — `Will reach 16% in M:SS` while the bar is actively
climbing, and `Starts rising to 26% in M:SS` during a pause (previously
`Next 26% in …`, which read as if it jumped there instantly). Backed by
a new `secondsToTarget` field on the shared wave state so the sim and
HUD stay in agreement. All display text goes through `translateText()` /
`en.json`.
<img width="278" height="116" alt="image"
src="https://github.com/user-attachments/assets/e0be3d2c-bb88-46be-b344-34d63e4859bd"
/>
<img width="304" height="171" alt="image"
src="https://github.com/user-attachments/assets/da74bd05-0b9a-4aec-bbf5-e7380fbda88e"
/>

**Danger skull:** while a side is below the bar in the warn window, its
on-map skull now blinks progressively faster as the countdown runs out
(accelerating to the moment the drain begins), then holds steady once it
is actually draining — a clearer "you are about to be hit" cue.

Rationale: the previous schedule removed players heavily in the first
half of a match and could leave a drawn-out endgame. Holding the clock
at 0% early keeps the opening about fighting, and concentrating its
pressure in the back half reserves it for actually breaking stalemates.
Values are tuning starting points and easy to adjust in
`DoomsdayClock.ts` / the config defaults.

## 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

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

<add your Discord username>

resources/lang/en.json

@@ -404,9 +404,9 @@
     "collapsing": "Collapsing -{rate}/s",
     "decay_in": "Decay in {secs}s",
     "final": "Final zone, hold {pct}%",
-    "growing": "Rising to {pct}%",
+    "growing": "Will reach {pct}% in {time}",
     "hold": "Hold ≥ {pct}%",
-    "next_wave": "Next {pct}% in {time}",
+    "next_wave": "Starts rising to {pct}% in {time}",
     "stable": "Stable",
     "title": "Doomsday Clock",
     "unstable": "Unstable",