docker: update to unified binary deployment

docker/Dockerfile

···
 FROM docker.io/golang:1.24-alpine3.21 AS build
 
 ENV CGO_ENABLED=1
+WORKDIR /usr/src/app
+COPY go.mod go.sum ./
 
 RUN apk add --no-cache gcc musl-dev
-
-WORKDIR /usr/src/app
-
-COPY go.mod go.sum ./
 RUN go mod download
 
 COPY . .
 RUN go build -v \
-    -o /usr/local/bin/knotserver \
+    -o /usr/local/bin/knot \
     -ldflags='-s -w -extldflags "-static"' \
-    ./cmd/knotserver && \
-    go build -v \
-    -o /usr/local/bin/keyfetch \
-    ./cmd/keyfetch && \
-    go build -v \
-    -o /usr/local/bin/repoguard \
-    ./cmd/repoguard
+    ./cmd/knot
 
 FROM docker.io/alpine:3.21
 
···
     head -c 32 /dev/random | base64 | tr -dc 'a-zA-Z0-9' | passwd git --stdin && \
     mkdir /app && mkdir /home/git/repositories
 
-COPY --from=build /usr/local/bin/knotserver /usr/local/bin
-COPY --from=build /usr/local/bin/keyfetch /usr/local/libexec/tangled-keyfetch
-COPY --from=build /usr/local/bin/repoguard /home/git/repoguard
+COPY --from=build /usr/local/bin/knot /usr/local/bin
 COPY docker/rootfs/ .
 
-RUN chown root:root /usr/local/libexec/tangled-keyfetch && \
-    chmod 755 /usr/local/libexec/tangled-keyfetch
-
 EXPOSE 22
 EXPOSE 5555
 
-ENTRYPOINT ["/bin/sh", "-c", "chown git:git /home/git/repoguard && chown git:git /app && chown git:git /home/git/repositories && /init"]
+ENTRYPOINT ["/bin/sh", "-c", "chown git:git /app && chown git:git /home/git/repositories && /init"]

docker/rootfs/etc/s6-overlay/s6-rc.d/knotserver/run

···
 #!/command/with-contenv ash
 
-exec s6-setuidgid git /usr/local/bin/knotserver
+exec s6-setuidgid git /usr/local/bin/knot server

docker/rootfs/etc/ssh/sshd_config.d/tangled_sshd.conf

···
 PasswordAuthentication no
 
 Match User git
-  AuthorizedKeysCommand /usr/local/libexec/tangled-keyfetch -git-dir /home/git/repositories
+  AuthorizedKeysCommand /usr/local/bin/knot keys -o authorized-keys
   AuthorizedKeysCommandUser nobody