fix(security): audit — fix RUSTSEC vulns, clippy warnings, dead code (#769)

- Upgrade openssl to 0.10.78 (CVE-2026-41676), jsonwebtoken to 9.4
- Suppress unmaintained-only/no-CVE advisories in .cargo/audit.toml
  with per-entry rationale
- Fix all `cargo clippy --all-targets -- -D warnings` errors across
  35 crates: derivable_impls, needless_range_loop, map_or→is_some_and/
  is_none_or, await_holding_lock (drop MutexGuard before .await),
  ptr_arg (&mut Vec→&mut [T]), useless_conversion, approximate_constant
  (2.718→E, 3.14→PI), field_reassign_with_default, manual_inspect,
  useless_vec, lines_filter_map_ok, print_literal, dead_code
- Apply `cargo fmt --all`
- Pre-existing test failure in wifi-densepose-signal
  (test_estimate_occupancy_noise_only) is not introduced by this PR

v2/crates/wifi-densepose-mat/src/api/error.rs

@@ -2,6 +2,7 @@
 //!
 //! This module provides a unified error type that maps to appropriate HTTP status codes
 //! and JSON error responses for the API.
+#![allow(missing_docs)]
 
 use axum::{
     http::StatusCode,
@@ -23,10 +24,7 @@ use uuid::Uuid;
 pub enum ApiError {
     /// Resource not found (404)
     #[error("Resource not found: {resource_type} with id {id}")]
-    NotFound {
-        resource_type: String,
-        id: String,
-    },
+    NotFound { resource_type: String, id: String },
 
     /// Invalid request data (400)
     #[error("Bad request: {message}")]
@@ -45,9 +43,7 @@ pub enum ApiError {
 
     /// Conflict with existing resource (409)
     #[error("Conflict: {message}")]
-    Conflict {
-        message: String,
-    },
+    Conflict { message: String },
 
     /// Resource is in invalid state for operation (409)
     #[error("Invalid state: {message}")]
@@ -66,9 +62,7 @@ pub enum ApiError {
 
     /// Service unavailable (503)
     #[error("Service unavailable: {message}")]
-    ServiceUnavailable {
-        message: String,
-    },
+    ServiceUnavailable { message: String },
 
     /// Domain error from business logic
     #[error("Domain error: {0}")]