fix(simulation): address PR #87 review — name collision, validation, and polish

- Fix critical name collision: shuffle+pop for unique NPC names (#3)
- Validate population_density >= 1 in generator and validator (#4)
- Guard against empty given_names/roles with validator warnings (#5)
- Extract filler word cap to MAX_FILLER_WORDS constant (#6)
- Fix cultural behavior gate checking wrong field (#7)
- Document intentional one-directional relationships (#8)
- Validate min_npcs <= max_npcs in validator (#9)
- Fix validate-ron script realpath error handling (#10)
- Add TODO comments for spike-specific code duplication (#11, #12, #13)

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

server/src/bin/validate_ron.rs

@@ -49,6 +49,27 @@ fn main() {
             Ok(spec) => {
                 println!("Valid ZoneSpec: {} ({})", spec.label, spec.zone_type);
                 println!("  {} roles, {} social sites", spec.roles.len(), spec.social_sites.len());
+                let mut warnings = 0;
+                if spec.roles.is_empty() {
+                    eprintln!("  WARNING: no roles defined — generator will reject this");
+                    warnings += 1;
+                }
+                if spec.population_density < 1 {
+                    eprintln!("  WARNING: population_density is 0 — generator requires >= 1");
+                    warnings += 1;
+                }
+                for site in &spec.social_sites {
+                    if site.min_npcs > site.max_npcs {
+                        eprintln!(
+                            "  WARNING: social site '{}' has min_npcs ({}) > max_npcs ({})",
+                            site.site_type, site.min_npcs, site.max_npcs
+                        );
+                        warnings += 1;
+                    }
+                }
+                if warnings > 0 {
+                    process::exit(1);
+                }
             }
             Err(e) => {
                 eprintln!("Invalid ZoneSpec in {}:", args.file);
@@ -69,6 +90,14 @@ fn main() {
                     profile.speech.filler_words.len(),
                     profile.values.favored_traits.len()
                 );
+                let mut warnings = 0;
+                if profile.naming.given_names.is_empty() {
+                    eprintln!("  WARNING: no given_names — generator will reject this");
+                    warnings += 1;
+                }
+                if warnings > 0 {
+                    process::exit(1);
+                }
             }
             Err(e) => {
                 eprintln!("Invalid CultureProfile in {}:", args.file);