fix: Dockerfile → COPY pre-built binary (no network needed)

Docker Desktop Windows blocks build network access. Instead of
building V from source inside Docker, cross-compile Linux binary
on host and COPY into minimal alpine image.

Dockerfile

@@ -1,17 +1,11 @@
-# ── Build: use official V container to compile ────────────────────────────
-FROM thevlang/vlang:alpine AS builder
-
-# Copy project source and build
-WORKDIR /src
-COPY . .
-RUN git clone https://github.com/vlang/yaml.git /root/.vmodules/yaml
-RUN v -prod -o /ntfy-bridge .
-
-# ── Runtime: minimal image ────────────────────────────────────────────────
+# ── Minimal Docker image for ntfy-bridge ──────────────────────────────────
+# Binary is built on the host:  v -os linux -o ntfy-bridge .
 FROM alpine:3.20
 
 RUN apk add --no-cache ca-certificates tzdata curl
-COPY --from=builder /ntfy-bridge /usr/local/bin/ntfy-bridge
+
+COPY ntfy-bridge /usr/local/bin/ntfy-bridge
+RUN chmod +x /usr/local/bin/ntfy-bridge
 
 WORKDIR /etc/ntfy-bridge
 EXPOSE 9090