ax(mining): replace prose comments with usage examples in miner_factory.go

AX Principle 2 — comments must show usage, not restate the signature.
MinerConstructor, MinerFactory, and NewMinerFactory had prose descriptions
that added no information beyond what the type already states.

Co-Authored-By: Charon <charon@lethean.io>

pkg/mining/miner_factory.go

@@ -5,10 +5,11 @@ import (
 	"sync"
 )
 
-// MinerConstructor is a function that creates a new miner instance
+// f.Register("custom", func() Miner { return NewCustomMiner() })
 type MinerConstructor func() Miner
 
-// MinerFactory handles miner instantiation and registration
+// factory := NewMinerFactory()
+// factory.Register("xmrig", func() Miner { return NewXMRigMiner() })
 type MinerFactory struct {
 	mu           sync.RWMutex
 	constructors map[string]MinerConstructor
@@ -18,7 +19,8 @@ type MinerFactory struct {
 // globalFactory is the default factory instance
 var globalFactory = NewMinerFactory()
 
-// NewMinerFactory creates a new MinerFactory with default miners registered
+// factory := NewMinerFactory()
+// factory.Register("xmrig", func() Miner { return NewXMRigMiner() })
 func NewMinerFactory() *MinerFactory {
 	f := &MinerFactory{
 		constructors: make(map[string]MinerConstructor),