chore(security,refactor): extract sanitization and improve code quality (#41)

* chore(security,refactor): extract sanitization and improve code quality

- [x] Extract sanitization functions to dedicated sanitization.go module
- [x] Add comprehensive golangci-lint v2 configuration with security rules
- [x] Replace interface{} with any type throughout codebase
- [x] Add admin API authentication security warning
- [x] Extract WebSocket and stats streaming constants
- [x] Add best-effort error handling comments for resource cleanup
- [x] Expand sensitive field patterns for improved PII redaction
- [x] Simplify safety checks and remove redundant nil validations
- [x] Improve test coverage for password field redaction patterns

* refactor: replace interface{} with any type alias

- [x] Replace all `map[string]interface{}` with `map[string]any`
- [x] Replace all `interface{}` with `any` in function signatures and type definitions
- [x] Update sync.Pool New function returns from `interface{}` to `any`
- [x] Add package documentation comments to 8 package files
- [x] Update type assertions and casts to work with `any` type

cache/redis/redis.go

@@ -1,3 +1,6 @@
+// Package libpack_cache_redis provides a Redis-backed cache implementation
+// for distributed caching across multiple proxy instances. Supports key
+// prefixing for multi-tenant isolation.
 package libpack_cache_redis
 
 import (
@@ -42,7 +45,7 @@ func New(redisClientConfig *RedisClientConfig) (*RedisConfig, error) {
 		ctx:    context.Background(),
 		prefix: redisClientConfig.Prefix,
 		builderPool: &sync.Pool{
-			New: func() interface{} {
+			New: func() any {
 				return &strings.Builder{}
 			},
 		},