fix: add yaml dependency to v.mod + Dockerfile v install yaml

The thevlang/vlang:alpine container doesn't include the yaml
module. Added it as a declared dependency and install step.

Dockerfile

@@ -4,6 +4,7 @@ FROM thevlang/vlang:alpine AS builder
 # Copy project source and build
 WORKDIR /src
 COPY . .
+RUN v install yaml
 RUN v -prod -o /ntfy-bridge .
 
 # ── Runtime: minimal image ────────────────────────────────────────────────

v.mod

@@ -3,6 +3,6 @@ Module {
     description: 'Homelab notification hub — aggregates Gitea, Docker, Uptime Kuma → Ntfy'
     version: '0.5.0'
     license: 'MIT'
-    dependencies: []
+    dependencies: ['https://github.com/vlang/yaml']
     subdirs: ['sources']
 }