feat: add CLI with Cobra and timestamped logging

Introduce structured CLI argument parsing using Cobra with three
configurable flags:
  --vendor: USB vendor ID (default: 0x0fcf)
  --product: USB product ID (default: 0x1008)
  --device: ANT+ device number (default: 3001)

Add timestamped logging for all log statements with format
YYYY-MM-DD HH:MM:SS. Log vendor, product, and device values at
startup in both hex and decimal.

Remove hardcoded USB identifiers from main.go and consolidate all
startup logic into cli.go with a dedicated Config struct.

Update ant.go ListenForTrainer signature to accept uint16 for
vendor and product IDs.

Makefile

@@ -15,7 +15,7 @@ vet: fmt
 
 build: vet
 	mkdir -p bin
-	go build -ldflags "-X main.Version=$(shell git rev-parse HEAD ) -X main.BuildTime=$(shell date +'%Y-%m-%dT%H:%M:%S')" -o bin ./cmd/...
+	go build -ldflags "-X main.Version=$(shell git rev-parse HEAD ) -X main.BuildTime=$(shell date +'%Y-%m-%dT%H:%M:%S')" -o bin/bridge ./cmd/...
 
 install: build
 	go install ./...