feat(core): refactor linters config and improve code quality (#119)

- [x] Reorganize golangci-lint configuration with documented disable reasons
- [x] Simplify errcheck and revive linter rules with targeted exclusions
- [x] Pre-compile regex patterns in input_validation.go for performance
- [x] Fix type assertions in memory_shard.go and resp.go with safety checks
- [x] Replace string comparison with EqualFold for case-insensitive matching
- [x] Fix loop variable captures in jwk.go and logout.go
- [x] Change high goroutine log level from Info to Debug in autocleanup.go
- [x] Replace deprecated "cancelled" spelling with "canceled" throughout
- [x] Add nolint annotations for intentional unused parameters
- [x] Improve comment formatting for deprecated functions
- [x] Fix comment spelling: "marshalling" → "marshaling"
- [x] Refactor provider warnings formatting in internal/providers/warnings.go
- [x] Simplify metrics summary building in internal/recovery/metrics.go
- [x] Pre-allocate slice in error_recovery.go GetDegradedServices
- [x] Refactor context cancellation checks in redis.go

config_marshalling.go

@@ -7,7 +7,7 @@ import (
 // REDACTED is the placeholder value for sensitive information
 const REDACTED = "[REDACTED]"
 
-// MarshalJSON implements custom JSON marshalling to redact sensitive fields
+// MarshalJSON implements custom JSON marshaling to redact sensitive fields
 // Rewritten without type aliases for yaegi compatibility
 func (c Config) MarshalJSON() ([]byte, error) {
 	// Build a map manually to avoid type alias issues with yaegi
@@ -47,7 +47,7 @@ func (c Config) MarshalJSON() ([]byte, error) {
 	return json.Marshal(result)
 }
 
-// MarshalYAML implements custom YAML marshalling to redact sensitive fields
+// MarshalYAML implements custom YAML marshaling to redact sensitive fields
 // Rewritten without type aliases for yaegi compatibility
 func (c Config) MarshalYAML() (interface{}, error) {
 	// Build a map manually to avoid type alias issues with yaegi