fix: resolve all linting and formatting issues

- Fix error return value checks (errcheck)
- Fix unused parameters by using underscore prefix
- Add missing package comments to all packages
- Fix context key type issue in middleware (use typed contextKey)
- Replace deprecated trace.NewNoopTracerProvider with noop.NewTracerProvider
- Fix embedded field selector in database client
- Remove trailing whitespace
- Remove revive linter (as requested) to avoid stuttering warnings for public API interfaces

All linting and formatting checks now pass.

internal/errorbus/channel_bus.go

@@ -1,3 +1,4 @@
+// Package errorbus provides a channel-based error bus implementation.
 package errorbus
 
 import (
@@ -11,17 +12,17 @@ import (
 
 // ChannelBus implements a channel-based error bus.
 type ChannelBus struct {
-	errors    chan errorWithContext
-	logger    logger.Logger
-	done      chan struct{}
-	wg        sync.WaitGroup
-	once      sync.Once
+	errors chan errorWithContext
+	logger logger.Logger
+	done   chan struct{}
+	wg     sync.WaitGroup
+	once   sync.Once
 }
 
 type errorWithContext struct {
-	err     error
-	ctx     context.Context
-	stack   []byte
+	err   error
+	ctx   context.Context
+	stack []byte
 }
 
 // NewChannelBus creates a new channel-based error bus.
@@ -162,4 +163,3 @@ func (b *ChannelBus) Close() error {
 
 // Ensure ChannelBus implements ErrorPublisher
 var _ errorbus.ErrorPublisher = (*ChannelBus)(nil)
-