Fix stale removal comments (persistent, not destroy) + add deterministic install test

- The remove_* comments still described the superseded "disable -> drain -> destroy"
  flow; the code keeps hooks alive (persistent) and re-enables on re-install. Updated
  the comments to match, and corrected the XInput note (its detours return synthesized
  state and never call the trampoline, so destroying its vector is safe -- unlike the
  trampoline-calling present/MKB/focus-cursor hooks).
- hook_install_test: a fast, single-threaded contract test for hook_install.hpp --
  install_inline creates the hook once and reuses the SAME trampoline across 50
  install/remove cycles (never freed -> no stale-detour UAF), toggling enable/disable
  cleanly. Fills the guard the removed (flaky, concurrency-bound) reproducer left, with
  no threads so it can't flake on SafetyHook's enable/disable atomicity.

x64 23/23, x86 3/3.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hook/src/present_hook.cpp

@@ -995,12 +995,12 @@ bool install_present_hooks(IpcClient& ipc)
 
 void remove_present_hooks()
 {
-	// DISABLE (not destroy) the hooks first: this restores the Present/Present1/ECL bytes under
-	// thread suspension so no NEW detour starts, but KEEPS the trampolines alive -- an in-flight
-	// detour about to call g_hk_present.stdcall() (the trampoline) must not have it freed under it.
-	// Destroying here (= {}) frees the trampoline immediately; at a few hundred presents/s that race
-	// was rarely hit, but the uncapped mock-game storm (thousands/s) hits it reliably (0xC0000005).
-	// So: disable -> drain (in-flight detours finish on the live trampoline) -> only THEN destroy.
+	// DISABLE (persistent model -- never destroy during the session): this restores the
+	// Present/Present1/ECL bytes under thread suspension so no NEW detour starts, while KEEPING the
+	// trampolines alive -- an in-flight detour about to call g_hk_present.stdcall() (the trampoline)
+	// must never have it freed under it (destroying = {} would, an AV the thousands/s storm hits
+	// reliably). So: disable -> drain (in-flight detours finish on the live trampoline) -> leave the
+	// hooks alive (re-install re-enables them; see hook_install.hpp).
 	disable_for_removal(g_hk_present);
 	disable_for_removal(g_hk_present1);
 	disable_for_removal(g_hk_ecl);