feat(webhook): Forgejo package webhook \u2192 ArgoCD image promotion (#54)

Replaces ArgoCD Image Updater with a webhook-driven approach.

When Forgejo fires X-Gitea-Event: package (action: created, type: container):
1. Extract image owner+name+version from payload
2. Look up in static promotion table (10 images \u2192 ArgoCD apps)
3. Fetch digest from Forgejo registry v2 API (Basic auth, REGISTRY_PAT)
4. Read-modify-write ArgoCD Application CR via k8s API (in-cluster SA token)
   - kustomize: JSON Patch /spec/sources[N]/kustomize/images
   - helm:      JSON Patch /spec/source/helm/parameters (runner.image.*)
5. Send Gotify notification with promotion result

Key design:
- Raw http.Client only \u2014 no client-go dependency
- context.Context propagated through all outbound calls
- Retry up to 3x on 409 Conflict (concurrent poimen-toolkit promotions)
- Request ID per invocation for log correlation
- Promotion table covers: api-gw, portfolio, poimen (3 sources), poimen-toolkit (2 images), forgejo-runner-{golang,node,rust}

RBAC: ClusterRole image-promoter (get+patch applications.argoproj.io) bound to api-gateway SA
NetworkPolicy: egress to cicd:3000 (registry) + default:443 (k8s API)
Deployment: REGISTRY_PAT from forgejo-registry-pat secret
13 tests in promoter_test.go, all pass

Closes #54

internal/webhook/forgejo.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"time"
 
 	"forgejo.riotpiao.com/rock/homelab-frontend/internal/notification"
 )
@@ -18,8 +19,9 @@ import (
 // ForgejoHandler receives Forgejo webhook payloads and forwards them to Gotify.
 // Forgejo sends a Gitea-compatible JSON payload with X-Gitea-Signature-256 header.
 type ForgejoHandler struct {
-	secret string
-	gotify *notification.GotifyClient
+	secret   string
+	gotify   *notification.GotifyClient
+	promoter *ImagePromoter
 }
 
 // NewForgejoHandler creates a handler from environment variables.
@@ -35,8 +37,9 @@ func NewForgejoHandler() *ForgejoHandler {
 	}
 
 	return &ForgejoHandler{
-		secret: os.Getenv("FORGEJO_WEBHOOK_SECRET"),
-		gotify: client,
+		secret:   os.Getenv("FORGEJO_WEBHOOK_SECRET"),
+		gotify:   client,
+		promoter: NewImagePromoter(),
 	}
 }
 
@@ -65,17 +68,23 @@ func (h *ForgejoHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	event := r.Header.Get("X-Gitea-Event")
+	if event == "" {
+		event = r.Header.Get("X-GitHub-Event")
+	}
+
+	// package events trigger image promotion; handled independently of Gotify
+	if event == "package" {
+		h.handlePackagePromotion(w, r, body)
+		return
+	}
+
 	if h.gotify == nil {
 		log.Printf("forgejo webhook received but Gotify not configured (GOTIFY_URL/GOTIFY_APP_TOKEN missing)")
 		w.WriteHeader(http.StatusOK)
 		return
 	}
 
-	event := r.Header.Get("X-Gitea-Event")
-	if event == "" {
-		event = r.Header.Get("X-GitHub-Event")
-	}
-
 	title, message, priority := h.formatMessage(event, body)
 	if title == "" {
 		// Unhandled event type — ack and ignore
@@ -99,6 +108,81 @@ func (h *ForgejoHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusOK)
 }
 
+// handlePackagePromotion processes a Forgejo package webhook event.
+// It promotes container images by patching ArgoCD Application CRs.
+// Sends a Gotify notification with the result (success or failure).
+func (h *ForgejoHandler) handlePackagePromotion(w http.ResponseWriter, r *http.Request, body []byte) {
+	// Generate a short request ID for correlating log lines from concurrent promotions.
+	reqID := fmt.Sprintf("%08x", time.Now().UnixNano()&0xFFFFFFFF)
+
+	var payload map[string]interface{}
+	if err := json.Unmarshal(body, &payload); err != nil {
+		log.Printf("forgejo webhook [%s]: package event: invalid JSON: %v", reqID, err)
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	action := fmt.Sprintf("%v", payload["action"])
+	if action != "created" {
+		// Ignore deletions and other actions
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	pkg, _ := payload["package"].(map[string]interface{})
+	pkgType := fmt.Sprintf("%v", pkg["type"])
+	if pkgType != "container" {
+		// Only promote container images
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	owner := jsonStr(pkg, "owner", "login")
+	name, _ := pkg["name"].(string)
+	version, _ := pkg["version"].(string)
+
+	if owner == "" || name == "" || version == "" {
+		log.Printf("forgejo webhook [%s]: package event: missing owner/name/version in payload", reqID)
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	image := fmt.Sprintf("forgejo.riotpiao.com/%s/%s", owner, name)
+	log.Printf("forgejo webhook [%s]: package event action=%s image=%s tag=%s", reqID, action, image, version)
+
+	var title, message string
+	var priority int
+
+	if h.promoter == nil {
+		title = fmt.Sprintf("📦 Image pushed: %s:%s", image, version)
+		message = "Image promotion disabled — REGISTRY_PAT not configured"
+		priority = 3
+		log.Printf("forgejo webhook [%s]: promoter disabled, image=%s tag=%s", reqID, image, version)
+	} else if err := h.promoter.Promote(r.Context(), image, version); err != nil {
+		title = fmt.Sprintf("❌ Promotion failed: %s:%s", image, version)
+		message = err.Error()
+		priority = 8
+		log.Printf("forgejo webhook [%s]: image promotion failed: %v", reqID, err)
+	} else {
+		title = fmt.Sprintf("🚀 Promoted: %s:%s", image, version)
+		message = "ArgoCD Application patched — redeployment triggered"
+		priority = 5
+		log.Printf("forgejo webhook [%s]: promoted image=%s tag=%s", reqID, image, version)
+	}
+
+	if h.gotify != nil && title != "" {
+		if _, err := h.gotify.SendMessage(notification.GotifyMessage{
+			Title:    title,
+			Message:  message,
+			Priority: priority,
+		}); err != nil {
+			log.Printf("forgejo webhook: failed to send gotify notification: %v", err)
+		}
+	}
+
+	w.WriteHeader(http.StatusOK)
+}
+
 // verifySignature checks X-Gitea-Signature-256: sha256=<hex>
 func (h *ForgejoHandler) verifySignature(body []byte, sig string) bool {
 	sig = strings.TrimPrefix(sig, "sha256=")