fix(simulation): address PR #89 review — version comment, settings contract, docs, dead process recovery

Must-fix: protocol version comment now references PROTOCOL_VERSION
(no hardcoded number), settings delete is idempotent no-op.

Suggestions addressed: BehaviorModifier dedup claim dropped, hash
collision safety documented, FK pragma in test store, columns_to_value
consolidated, modifier_hint mismatch logging, OffDuty test coverage,
batching tradeoff documented, unknown value_type warning, occluded
text risk documented, dead child respawn in voice worker, INJECT
block ambiguity documented.

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

server/src/bridge/types.rs

@@ -84,7 +84,7 @@ pub struct StartupMessage {
 /// Future fields: ambient sound events, HUD state (D-020 expansion).
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ObserverSnapshot {
-    /// Protocol version for forward compatibility. Current: 19.
+    /// Protocol version for forward compatibility. See [`PROTOCOL_VERSION`].
     pub version: u8,
     /// Simulation tick when this snapshot was produced
     pub tick: u64,