add Dockerfile and docker-compose for multi-stage build; update .gitignore and various HTML examples

Dockerfile

@@ -0,0 +1,24 @@
+# Multi-stage Dockerfile for Go (PocketBase) project
+# --- Build Stage ---
+FROM golang:1.21-alpine AS builder
+WORKDIR /app
+COPY go.mod .
+COPY go.sum .
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -o server main.go
+
+# --- Development Stage ---
+FROM golang:1.21-alpine AS dev
+WORKDIR /app
+COPY --from=builder /app /app
+EXPOSE 8080
+CMD ["go", "run", "main.go"]
+
+# --- Production Stage ---
+FROM alpine:3.18 AS prod
+WORKDIR /app
+COPY --from=builder /app/server /app/server
+COPY pb_public /app/pb_public
+EXPOSE 8080
+CMD ["/app/server"]