feat(simulation): interaction tracking + trust progression (#325, #324)

InteractionMemory component tracks interaction_count, last_interaction_tick,
and notable_events per NPC. Drives D-028 Layer 2 situation activation:
first_meeting (count==0) and repeated_visit (count>=3). warm_active in mood
system now derives from InteractionMemory within a 300-tick window.

Trust progression wired into dialogue systems: talk completion (+1),
walk-away (-1), confrontation (-2) emit TrustEvents consumed by update_trust.
InteractionEvent (WalkAway, Confrontation) recorded in notable_events for
fast per-pair access.

Adds FirstMeeting and RepeatedVisit Situation variants. 18 unit tests in
interaction.rs. All arithmetic integer-only (D-010 determinism). No HashMap.

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

server/src/content/line_pool.rs

@@ -94,6 +94,10 @@ pub enum Situation {
     Emergency,
     Routine,
     Observation,
+    /// First player-NPC interaction — interaction_count == 0 (#325, D-028 Layer 2).
+    FirstMeeting,
+    /// Player has talked to this NPC 3+ times — interaction_count >= 3 (#325, D-028 Layer 2).
+    RepeatedVisit,
 }
 
 impl FromStr for Situation {
@@ -113,6 +117,8 @@ impl FromStr for Situation {
             "emergency" => Ok(Self::Emergency),
             "routine" => Ok(Self::Routine),
             "observation" => Ok(Self::Observation),
+            "first_meeting" => Ok(Self::FirstMeeting),
+            "repeated_visit" => Ok(Self::RepeatedVisit),
             _ => Err(ParseEnumError {
                 kind: "Situation",
                 value: s.to_string(),