Fix stale comments

- hook_guard.hpp top block: described removal as `hook = {}` (destroy/reset); the
  model is now persistent disable_for_removal (never destroyed mid-session, the
  trampoline stays alive). Updated to match.
- input_source.hpp: SteamInputSource is no longer "future" -- it exists and is
  opt-in; reworded.
- audio_ring.hpp: format_generation actually bumps on every set_format (not
  "reserved, v1 sets once"); verify_capture is a 4-byte atomic guarded by the
  version gate (not "repurposed from a reserved byte old builds saw"); and the
  SharedBlock is no longer "20-byte pads".
- audio_format_verifier.cpp: dropped a dead `(void)recover_layout;` with a stale
  "step (a) only" comment -- the parameter is actually used.

Comment-only except the dead (void) cast.

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

hook/src/hook_guard.hpp

@@ -7,13 +7,14 @@
 // use-after-free -> the game crashes (the "spamming Mirror video crashed Brotato" bug).
 //
 // The fix mirrors the audio hooks' epoch+drain pattern, generalised for inline hooks:
-//   1. Restore/disable the hook FIRST so no NEW detour can start. For a SafetyHook inline hook
-//      that's `hook = {}` (reset): it restores the original bytes under thread suspension, and
-//      its mutex-guarded call wrappers make any in-flight trampoline call safe. For a hook the
-//      game reaches by a cached pointer (Vulkan present, the WNDPROC subclass) it's clearing an
-//      atomic gate / restoring the window proc.
-//   2. drain() -- wait (bounded) for detour BODIES already running to finish, since the reset
-//      above does NOT wait for the part of the detour that runs before it calls the trampoline.
+//   1. Disable the hook FIRST so no NEW detour can start. For a SafetyHook inline hook that's
+//      `disable_for_removal(hook)` (disable, NOT `= {}` destroy): it restores the original bytes but
+//      keeps the trampoline alive -- hooks are PERSISTENT, never destroyed mid-session, so an in-flight
+//      detour about to call the trampoline never finds it freed (see hook_install.hpp). For a hook the
+//      game reaches by a cached pointer (Vulkan present, the WNDPROC subclass) it's clearing an atomic
+//      gate / restoring the window proc instead.
+//   2. drain() -- wait (bounded) for detour BODIES already running to finish, since the disable above
+//      does NOT wait for the part of the detour that runs before it calls the trampoline.
 //   3. Only THEN free the shared state the detour was reading.
 //
 // Each detour wraps its whole body in a DetourGate::Guard (an RAII active-count). drain() spins