SourceHook trampolines from MetaMod:Source don't fire under FEX — CounterStrikeSharp's Hook_StartupServer never executes on aarch64

**What Game**
Counter-Strike 2 Dedicated Server (Steam App ID 730, native x86_64 Linux build)
https://store.steampowered.com/app/730/CounterStrike_2/

**Describe the bug**
On Ampere A1 aarch64 (Ubuntu 22.04.5) running CS2 dedicated server through FEX-Emu, Metamod:Source 2.0.0-dev+1401 successfully loads CounterStrikeSharp (a .NET plugin host) as a plugin, but the SourceHook the plugin installs on `INetworkServerService::StartupServer` either never fires or fires with a context where the GameResourceServiceServer pointer is nullptr. Plugin-side effect: `globals::entitySystem` stays nullptr for the process lifetime, and every plugin event handler that traverses entities throws `Entity system yet is not initialized`.

Filed the CSS-side report at https://github.com/roflmuffin/CounterStrikeSharp/issues/1320 — cross-link so both projects see it.

Why this looks FEX-side, not CSS-side:
- The ianlucas/cs2-signatures tracker shows CSS as ✅ on Linux (native x86_64 testing). Signatures are correct.
- Other ARM/CS2 admins report the same class of bug under box64 (https://github.com/ptitSeb/box64/issues/2753) and zThundy/CS2-Server-on-ARM (README: "Plugins just don't work for me").
- The same binaries that fail today were working at one point in the same install — strongly suggests non-determinism in trampoline insertion under FEX translation. Same CS2 buildid `23371447` worked at May 23 02:01 UTC and broke after a single `systemctl restart` at 22:25 UTC.

**To Reproduce**
1. CS2 dedicated server on aarch64 + FEX-Emu, public 1.41.6.4 (buildid 23371447)
2. Install Metamod:Source 2.0.0-dev+1401 and CounterStrikeSharp v1.0.368 (or fork mrc4tt v1.0.384 — same result)
3. Drop in any CSS plugin that calls entity APIs (RetakesPlugin 3.0.4 + RetakesAllocator 2.4.2 reproduces consistently)
4. `systemctl start cs2.service`
5. Add a bot via RCON: `bot_add`
6. Server journal floods with `Entity system yet is not initialized` from every event handler that touches entities (OnPlayerSpawn, OnPlayerTeam, OnTick beam refresh, etc.)

**Expected behavior**
SourceHook trampoline fires on `INetworkServerService::StartupServer` invocation, just like on native x86_64. `globals::entitySystem` gets populated. Plugin entity APIs work normally.

**Screenshots**
N/A (server-side, logs only).

Sample exception:
```
CounterStrikeSharp.API.Core.NativeException: Entity system yet is not initialized
at CounterStrikeSharp.API.Core.NativeAPI.GetConcreteEntityListPointer() in .../Generated/Natives/API.cs:line 983
at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
at RetakesPlugin.Utils.PlayerHelper.IsValid(CCSPlayerController player)
at RetakesPlugin.Events.PlayerEventHandlers.OnPlayerSpawn(EventPlayerSpawn event, GameEventInfo info)
```

**Host (please complete the following information):**
- OS: Ubuntu 22.04.5 LTS
- Architecture: aarch64
- CPU: ARM Cortex-A78 (Ampere A1)
- Kernel: 6.x (Ubuntu 22.04 stock)

**FEX (please complete the following information):**
- FEX-Emu: `/usr/local/bin/FEXInterpreter` dated 2026-05-22 (binary, no --version flag exposed)
- Wine version: N/A (Linux-native binary)
- RootFS: Ubuntu_22_04

**CSS code path that's failing**
`src/mm_plugin.cpp` registers a SourceHook on `INetworkServerService::StartupServer`. The handler is meant to run:
```cpp
globals::entitySystem = interfaces::pGameResourceServiceServer->GetGameEntitySystem();
```
On FEX this assignment never produces a non-null `entitySystem`. CSS has no log line at hook entry, so I can't directly confirm whether the hook fires at all vs fires with a null `pGameResourceServiceServer`.

**What I tried that did NOT help**
- `DOTNET_EnableWriteXorExecute=0` (set), `DOTNET_TieredCompilation=0`, `DOTNET_ReadyToRun=0`, `DOTNET_EnableHWIntrinsic=0` — no change
- Multiple `systemctl restart cs2.service` cycles — deterministic failure (12 errors per bot join)
- `changelevel` via RCON to retrigger StartupServer — no change
- CS2 downgrade to buildid 23241720 (1.41.6.1) — no change
- CSS clean reinstall + community fork with hook fix — no change

**Asks**
- Is Metamod's SourceHook (https://github.com/alliedmodders/sourcehook) known to work under FEX? Any required `Config.json` settings (e.g., `TSOEnabled`, `MultiblockEnabled`, `JITX86InlineMemcpy`) that affect inline-hook trampolines?
- Is there a way to enable verbose FEX logging for the moment a trampoline is installed in JIT-translated code, to confirm whether the hook lands in a translated code region vs a fallback interpreter region?
- Any known interaction with .NET 8's `coreclr.so` initialization that could cause Metamod's hook to be overwritten?

Happy to provide additional FEX trace logs, gdb stacks, or test patches on request.