fix(render): foliage wind keys on the DAT-classified WeatherKind, not the day-group index (Campaign VM VM6)

FoliageWindByDayGroup / FoliageWindDayGroupPoint(int ActiveDayGroup, ...)
becomes FoliageWindByWeather / FoliageWindWeatherPoint(string WeatherKind,
...) in AtmospherePolicyDeclaration (Plugin.Abstractions is BCL-only, so
the key is the exact member name of AcDream.Core.World.WeatherKind rather
than the enum itself). The raw activeDayGroup index carries no weather
meaning by itself; WeatherState.cs already classifies each day group's
authored DAT name into one of five real weather kinds, and that fact was
already threaded through AtmosphericFrameInputs.Weather / uAtmosphereWeather.x
— this reuses it instead of guessing an index-to-category mapping.

Built-in table (BuiltInAtmosphericRenderPack.AtmospherePolicy()): Clear
0.25/0.15, Overcast 0.60/0.35, Rain 0.85/0.60, Snow 0.35/0.20, Storm
1.00/0.75 — all five WeatherKind members declared, the invented "Cloudy"
row dropped. RenderPackAtmospherePolicyEvaluation.FoliageWind now takes a
WeatherKind and matches by weather.ToString() (ordinal) against each
declared point's name; a kind absent from the table falls back to the
declared Clear row, then to (0,0) if Clear itself is undeclared. The
delta-seconds EMA interpolation (EaseTowardTarget) is unchanged.
AtmosphericPostProcessGraph.ResolveFoliageWind and its two callers
(RenderPostProcess via inputs.Weather; RenderDirectionalShadows via
foundation.Atmosphere.Kind) now pass WeatherKind instead of the day-group
int.

RenderPackValidation.ValidateAtmosphere (runs for every pack declaring an
AtmospherePolicy, not gated to Tier2/shadow packs) now rejects an unknown
or non-exact-case weather-kind name and a repeated kind, mirroring the
existing ActiveDayGroupMultiplier duplicate-key check.

Tests: RenderPackAtmospherePolicyEvaluationTests rewritten for the
kind-keyed API (all five kinds resolve to their declared row, an unlisted
kind falls back to Clear, ordinal exact-case matching, null-table
handling); RenderPackSpirvValidatorTests gains four descriptor-validation
cases (unknown name, wrong case, duplicate kind, the five-kind table
accepted); AtmosphericPostProcessGraphTests' three foliage-wind cases now
select WeatherKind.Storm via `with` instead of an assumed day-group index.

Spot-check (per the coordinator's ask, not changed here): yes —
ActiveDayGroupMultiplier / EvaluateDayGroupPolicy (pre-existing, Campaign
AR/VM3-era — BuiltInAtmosphericRenderPack.AtmospherePolicy()'s three rows
`new ActiveDayGroupMultiplier(0, 1.0), (1, 0.35), (2, 0.20)`) key the
sun-ray/shadow/volumetric day-group strength multiplier by the same raw
activeDayGroup index with an undocumented assumed meaning (0=brightest ...
2=dimmest), the identical class of issue this commit fixes for foliage
wind. Left unchanged per instruction; flagging for the coordinator to file.

Full solution Debug and Release builds green. App hermetic filter
6024/6026 — the same 2 pre-existing failures as VM6a/VM6b. Both were
re-run in isolation per the verification ask: both still fail alone (not
a load-flake in this environment) — confirmed via git stash earlier this
session that both already fail on the unmodified pre-VM6 baseline, so
they are pre-existing and unrelated to this change. Core.Tests hermetic
4697/4697. RenderPackValidator.Tests 30/30. No shader/spv changes in this
commit (pure C#/docs fix).

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

tests/AcDream.App.Tests/Rendering/Packs/AtmosphericPostProcessGraphTests.cs

@@ -1228,11 +1228,12 @@ public sealed class AtmosphericPostProcessGraphTests
         var device = new RecordingGpuDevice();
         using var graph = Graph(device, "medium", windClockSecondsOverride: 12f);
         graph.PrepareWorldTarget(640, 480, 1);
-        // Rainy (index 3 in the built-in table) is the highest declared
-        // mean/gust — the exact target does not matter here, only that the
-        // gate still zeroes the output despite a nonzero smoothed target.
-        AtmosphericFrameInputs indoors = Inputs(640, 480, activeDayGroup: 3) with
+        // Storm is the highest declared mean/gust — the exact target does
+        // not matter here, only that the gate still zeroes the output
+        // despite a nonzero smoothed target.
+        AtmosphericFrameInputs indoors = Inputs(640, 480) with
         {
+            Weather = WeatherKind.Storm,
             IsOutdoor = false,
         };
 
@@ -1252,7 +1253,7 @@ public sealed class AtmosphericPostProcessGraphTests
             windClockSecondsOverride: 12f,
             userSettingOverrides: new Dictionary<string, string> { ["wind-enabled"] = "false" });
         graph.PrepareWorldTarget(640, 480, 1);
-        AtmosphericFrameInputs outdoors = Inputs(640, 480, activeDayGroup: 3);
+        AtmosphericFrameInputs outdoors = Inputs(640, 480) with { Weather = WeatherKind.Storm };
 
         AtmosphericFrameUniforms atmospheric = RenderAndReadFrameBlock(device, graph, outdoors);
 
@@ -1290,7 +1291,7 @@ public sealed class AtmosphericPostProcessGraphTests
         IGpuRenderTarget world = graph.PrepareWorldTarget(640, 480, 1);
         using IGpuFrame frame = device.BeginFrame();
         RecordWorldPass(frame, world);
-        AtmosphericFrameInputs inputs = Inputs(640, 480, activeDayGroup: 3);
+        AtmosphericFrameInputs inputs = Inputs(640, 480) with { Weather = WeatherKind.Storm };
 
         graph.RenderPostProcess(frame, in inputs);
         AtmosphericFrameUniforms first = ReadLastFrameBlock(device);