Add the runnable Gitea, PostgreSQL, and Hop control-plane foundation

Hop-State: A_06FN3QYA1N56NQYGZ81DWGR
Hop-Proposal: R_06FN3QXJRYPPEQZQA6S69QG
Hop-Task: T_06FN3MVGY3MT82ESQ89BND0
Hop-Attempt: AT_06FN3MVGY092BFA5MR9C7EG

services/control-plane/internal/gitea/webhook.go

@@ -0,0 +1,17 @@
+package gitea
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+)
+
+func VerifySignature(body []byte, signature, secret string) bool {
+	provided, err := hex.DecodeString(signature)
+	if err != nil {
+		return false
+	}
+	mac := hmac.New(sha256.New, []byte(secret))
+	_, _ = mac.Write(body)
+	return hmac.Equal(provided, mac.Sum(nil))
+}