fix(server): address PR #23 review — 4 critical bugs, 3 warnings, 11 suggestions

Critical fixes:
- Add PendingRecognitionWire serialization roundtrip test
- Check Option return from delay.cancel() before logging
- InputQueue capacity limit (1000) with drop-oldest and warning
- TODO in observation.rs references ticket #450

Warning fixes:
- Hot-reload guards against invalid/empty content root
- Location header mismatch warning in line pool indexing
- walk_yaml() depth limit (100) against symlink loops
- Consecutive reload failure counter (warns after 5+)

Test additions:
- Negative prerequisite filtering test for monologue lines
- Integration test for pending_recognitions in observer snapshot
- Eavesdrop threshold ordering assertion (Careful < default)

Documentation:
- Playtesting expectation comments on delay constants
- is_pending() scalability note for future NPC cognitive delay
- ID format regex validation in line pool spec
- BTreeMap vs sort() ordering clarification in loader
- Multiplayer TODO in relationships.rs references D-010
- ContentSlug ticket #452 filed for entity slug resolution

394 tests, 0 failures.

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

server/src/npc/relationships.rs

@@ -26,11 +26,8 @@ pub struct RelationshipEdge {
 /// BTreeMap<(subject, target), edge> for deterministic iteration (D-010).
 /// Directed graph: edge (A, B) represents how A feels about B.
 ///
-/// TODO(v0.2): This is a global omniscient resource — all entities share one
-/// graph. This violates information boundaries (D-009/D-010) because any
-/// system can read any relationship. For multiplayer, this needs per-observer
-/// projection so each entity only sees relationships they should know about.
-/// Acceptable for v0.1 single-player where the server is authoritative.
+/// TODO(v0.2): RelationshipGraph is per-world. Multiplayer needs per-observer
+/// relationship views (D-010).
 #[derive(Resource, Debug, Clone, Default, Serialize, Deserialize)]
 pub struct RelationshipGraph {
     edges: BTreeMap<(StableId, StableId), RelationshipEdge>,