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Delete the hand-authored YAML content pipeline (server/src/content/) superseded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/tests/triangle_validation.rs

@@ -9,7 +9,7 @@
 //!   `cargo test -p settled-reach-server -- triangle_validation`
 
 use settled_reach_server::{
-    content::template::{
+    simulation::triangle::{
         generate_cross_template_triangles, generate_intra_template_triangles,
         validate_triangle_def, ConflictType, NpcAxis, RelationshipConstraint, RoleId,
         TemplateId, TemplateOwnership, TriangleDef, TriangleId, TrianglePhase, TrustRange,