tools(ace-mods): add @settime ACE mod for same-clock retail/acdream sky comparisons

Sky and weather gates need retail and acdream looking at the SAME Dereth
hour and the SAME authored day group; until now the only lever was
acdream's ACDREAM_WORLD_TIME/ACDREAM_DAY_GROUP pins, which retail cannot
follow, so the user could never judge night-sky differences (aurora,
dome edge) side by side.

@settime <hour|fraction> [Sunny|Rainy|Clear|Cloudy|<index>] jumps ACE's
Timers.PortalYearTicks FORWARD to the next matching instant. Every
TimeSync header carries that value, so both clients re-sync within
seconds. Forward-only because DelayActions compare against the same
clock (a backward jump would stall them). The calendar and day-group
roll duplicate acdream's retail ports (DerethCalendar shift 3600,
SkyDayGroupSelector LCG from SkyDesc::CalcPresentDayGroup @0x00500E10)
and the 20-entry name table was dumped from the installed Region DAT.

Install: copy SetTime.dll + Meta.json to C:\ACE\Mods\SetTime and run
@mod find (or restart ACE). Dev servers only.

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

tools/ace-mods/SetTime/README.md

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+# SetTime — ACE mod for side-by-side sky/weather comparisons
+
+`@settime <hour|fraction> [Sunny|Rainy|Clear|Cloudy|<dayGroupIndex>]`
+
+Jumps the server's Dereth clock **forward** (never back) so retail and
+acdream — both driven by ACE's TimeSync — show the same hour and the same
+authored day group:
+
+- `@settime 3` → the next 3 o'clock (day fraction 0.125);
+- `@settime 0.125 Rainy` → 3 o'clock on the next day whose roll is a Rainy group;
+- `@settime 12 16` → noon on the next day that rolls day group 16.
+
+Dev servers only: a forward jump fires every pending `DelayAction` early.
+The command needs `AccessLevel.Admin`.
+
+## Build and install
+
+```powershell
+dotnet build tools/ace-mods/SetTime -c Release
+New-Item -ItemType Directory -Force C:\ACE\Mods\SetTime | Out-Null
+Copy-Item tools/ace-mods/SetTime/bin/Release/net10.0/SetTime.dll, tools/ace-mods/SetTime/Meta.json C:\ACE\Mods\SetTime\
+```
+
+Then restart ACE (the mod loader also hot-reloads when `HotReload` is true).
+`AceServerDir` (default `C:\ACE\Server`) can be overridden with
+`-p:AceServerDir=...` if the server lives elsewhere.
+
+The calendar and day-group roll are the same retail ports acdream uses
+(`DerethDateTime`, `SkyDayGroupSelector`; retail
+`SkyDesc::CalcPresentDayGroup @0x00500E10`), so the group the command
+predicts is the group both clients will render.