style: clippy-1.93 machine-applicable auto-fixes (#967)

cargo clippy --fix on files the new clippy (1.93) flags: unused imports
(name_index, storyteller), manual_range_contains (block_irregularity),
length-comparison/is_empty (layer3, serialization). All behavior-preserving.
Surfaced because a warm target/ makes the pre-push hook actually run clippy
(it skips on cold worktrees). Remaining non-auto-fixable test-code lints
tracked in #967.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/src/atlas/block_irregularity.rs

@@ -110,7 +110,7 @@ mod tests {
         for a in &archetypes {
             let v = block_irregularity(300, a);
             assert!(
-                v >= 0.05 && v <= 1.0,
+                (0.05..=1.0).contains(&v),
                 "archetype {:?} gave {v} out of [0.05, 1.0]",
                 a
             );

server/src/simulation/name_index.rs

@@ -184,7 +184,7 @@ fn collect_names(conn: &Connection) -> rusqlite::Result<Vec<(String, String)>> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use aho_corasick::{AhoCorasick, AhoCorasickBuilder, MatchKind};
+    use aho_corasick::{AhoCorasickBuilder, MatchKind};
 
     /// Build a minimal index directly (no DB) for unit testing.
     fn make_index(pairs: &[(&str, &str)]) -> SystemNameIndex {

server/src/storyteller/mod.rs

@@ -1172,7 +1172,7 @@ mod tests {
     #[test]
     fn escalate_inserts_routine_deviation_on_triangle_npcs() {
         use crate::knowledge::registry::EntityRegistry;
-        use crate::knowledge::types::StableId;
+
         use crate::npc::{Npc, RoutineDeviation};
 
         let mut world = World::new();