refactor(simulation): address PR #32 review — 14 items from Hoshe + Tyre

Hoshe (code quality):
- Remove dead RoomMember component from reset.rs
- Remove execute_reset (dual API trap); plan_reset is sole production path
- .unwrap() → .expect() on reset_plate in setup_gauntlet boot path
- Add 10s read timeout to TCP runtime test (prevents hangs)
- Register player in EntityRegistry in runtime boot test
- Document room_at z-range and corridor overlap assumptions
- Derive entity count from EXPECTED_ENTITY_COUNT constant (was hardcoded 24)
- Add reset plate (49-51) verification to stable_id_ranges_match_spec
- Add debounce exact boundary test (tick 9 rejected, tick 10 accepted)

Tyre (architecture):
- Gate test_world rooms/constants/setup behind "gauntlet" feature (default-on);
  reset module stays always-compiled (production dependency via input system)
- Document setup_gauntlet scheduler bypass for future tracking
- Extract runtime TCP test to content_runtime.rs (separate failure modes)

507 tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/lib.rs

@@ -9,4 +9,7 @@ pub mod npc;
 pub mod perception;
 pub mod simulation;
 pub mod storyteller;
+// test_world::reset is always compiled (used by simulation::input).
+// Room definitions, constants, and setup_gauntlet are gated behind
+// the "gauntlet" feature (default-on) to allow stripping from release builds.
 pub mod test_world;