build: add VERSION-based release workflow

Introduce VERSION as the app version source of truth and add make bump-patch to increment VERSION, commit, and create a matching vX.Y.Z tag.

Wire VERSION into build outputs by injecting it into webterm.Version for make build-go and Docker image builds, and include VERSION in Docker build context.

Also remove the visible dashboard container count subtitle while keeping count updates in browser console logs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Dockerfile

@@ -7,7 +7,8 @@ WORKDIR /src
 COPY go/go.mod go/go.sum ./go/
 RUN cd go && go mod download
 COPY go ./go
-RUN cd go && CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /out/webterm ./cmd/webterm
+COPY VERSION ./VERSION
+RUN cd go && VERSION=$(cat /src/VERSION) && CGO_ENABLED=0 go build -trimpath -ldflags="-s -w -X github.com/rcarmo/webterm-go-port/webterm.Version=$VERSION" -o /out/webterm ./cmd/webterm
 
 FROM alpine:3.21 AS runtime