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/perception/cognitive_delay.rs

@@ -19,10 +19,22 @@ use crate::simulation::time::SimulationTime;
 
 /// Base cognitive delay: 0.6 seconds = 6 ticks at 10 tps (D-031, D-060).
 /// Tunable: expect playtesting adjustments.
+///
+/// Playtesting expectation: 0.6s should feel like a brief "processing" beat —
+/// noticeable enough that new entities register as grey blobs before resolving,
+/// but short enough to not feel sluggish. If playtesters report recognition
+/// feels instant (reduce to test), or laggy (current value may be too high for
+/// fast-paced encounters), adjust in 2-tick increments. The 2:1 ratio with
+/// URGENT_DELAY_TICKS should be preserved.
 pub const NORMAL_DELAY_TICKS: u64 = 6;
 
 /// Urgent cognitive delay: 0.3 seconds = 3 ticks at 10 tps (D-031, D-060).
 /// Triggered when observe_anomaly context is active.
+///
+/// Playtesting expectation: 0.3s should feel nearly instant but still register
+/// visually as a "snap to attention" moment. If playtesters don't notice the
+/// delay at all, consider whether the grey blob phase is too brief to read.
+/// Must remain strictly less than NORMAL_DELAY_TICKS.
 pub const URGENT_DELAY_TICKS: u64 = 3;
 
 /// How the recognition was triggered, determines delay duration.
@@ -76,6 +88,8 @@ impl CognitiveDelay {
     }
 
     /// Check if an entity is already pending recognition.
+    // Note: O(n) scan over pending vec. Fine for v0.1 (typically <10 pending).
+    // If NPC cognitive delay is added, consider HashSet<StableId> index.
     pub fn is_pending(&self, stable_id: &StableId) -> bool {
         self.pending.iter().any(|p| p.stable_id == *stable_id)
     }