security: Fix 10 vulnerabilities, remove 12 dead code instances

Critical fixes:
- Remove hardcoded admin/admin123 credentials from UserManager
- Enable JWT signature verification (was disabled for debugging)
- Redact secrets from /dev/config endpoint (was exposing os.environ)
- Remove hardcoded SSH admin/admin credentials from hardware service
- Add channel validation to prevent command injection in router interface

Rust fixes:
- Replace partial_cmp().unwrap() with .unwrap_or(Equal) to prevent
  NaN panics in 6 locations across core, signal, nn, mat crates
- Replace .expect()/.unwrap() with safe fallbacks in utils, csi_receiver
- Replace SystemTime unwrap with unwrap_or_default

Dead code removed:
- Duplicate imports (CORSMiddleware, os, Path, ABC, subprocess)
- Unused AdaptiveRateLimit/RateLimitStorage/RedisRateLimitStorage (~110 lines)
- Unused _log_authentication_event method
- Unused Confidence::new_unchecked in Rust
- Fix bare except: clause to except Exception:

https://claude.ai/code/session_01Ki7pvEZtJDvqJkmyn6B714

rust-port/wifi-densepose-rs/crates/wifi-densepose-mat/src/ml/debris_model.rs

@@ -164,7 +164,7 @@ impl DebrisClassification {
     pub fn new(probabilities: Vec<f32>) -> Self {
         let (max_idx, &max_prob) = probabilities.iter()
             .enumerate()
-            .max_by(|(_, a), (_, b)| a.partial_cmp(b).unwrap())
+            .max_by(|(_, a), (_, b)| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal))
             .unwrap_or((7, &0.0));
 
         // Check for composite materials (multiple high probabilities)
@@ -216,7 +216,7 @@ impl DebrisClassification {
         self.class_probabilities.iter()
             .enumerate()
             .filter(|(i, _)| *i != primary_idx)
-            .max_by(|(_, a), (_, b)| a.partial_cmp(b).unwrap())
+            .max_by(|(_, a), (_, b)| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal))
             .map(|(i, _)| MaterialType::from_index(i))
     }
 }

rust-port/wifi-densepose-rs/crates/wifi-densepose-mat/src/ml/vital_signs_classifier.rs

@@ -593,7 +593,7 @@ impl VitalSignsClassifier {
             .enumerate()
             .skip(1)  // Skip DC
             .take(30) // Up to ~30% of Nyquist
-            .max_by(|(_, a), (_, b)| a.partial_cmp(b).unwrap())
+            .max_by(|(_, a), (_, b)| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal))
             .unwrap_or((0, &0.0));
 
         // Store dominant frequency in last position