refactor(simulation): remove v0.1 content loading system (#655)

Delete the hand-authored YAML content pipeline (server/src/content/) superseded
by the v0.2 generator-first approach (D-122, D-128). Runtime ECS types that were
co-located with content loading have been extracted to dedicated simulation modules:

- simulation/triangle.rs: TriangleState, TriangleCrisisEventQueue, tick/resolve systems
- simulation/line_pool.rs: LinePoolIndex, AccessTier, TrustTier, Mood, LinePoolIndexResource
- simulation/knowledge_grant.rs: KnowledgeGrant, Prerequisites

Monologue systems (trigger_monologue, trigger_recognition_monologue,
trigger_event_monologue) now use hardcoded fallback lines only; the
ContentStoreResource branch and select_pool_line function are removed.

Deleted: content/{loader,types,line_pool,hot_reload,spawn,instantiation,entanglement,mod}.rs
Deleted: tests/{content_loading,content_runtime,content_scaling,template_instantiation,template_schema}.rs
Deleted: bin/line_preview.rs (v0.1 tool)

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

server/src/npc/mood.rs

@@ -18,7 +18,7 @@
 use bevy_ecs::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::content::line_pool::Mood as ContentMood;
+use crate::simulation::line_pool::Mood as ContentMood;
 use crate::npc::interaction::InteractionMemory;
 use crate::npc::{Npc, ToleranceThreshold};
 use crate::simulation::dialogue::CurrentMood;