Add ANI_CLI_WEB_BRANCH build arg

- add ANI_CLI_WEB_BRANCH to the Docker build so ani-cli-web can be cloned from master or another branch
- pass the new build arg through docker-compose
- document the new branch-selection workflow in the README

Dockerfile

@@ -5,6 +5,7 @@ ARG ANI_CLI_BRANCH=master
 ARG ANIKOTO_CLI=https://github.com/Slimyslushy/anikoto-cli.git
 ARG ANIKOTO_CLI_BRANCH=main
 ARG ANI_CLI_WEB=https://gitea.coreplay.eu/Dymas/ani-cli-web.git
+ARG ANI_CLI_WEB_BRANCH=main
 ARG YT_DLP_RELEASE_URL=https://github.com/yt-dlp/yt-dlp/releases/latest/download/yt-dlp
 
 ENV DEBIAN_FRONTEND=noninteractive \
@@ -13,6 +14,7 @@ ENV DEBIAN_FRONTEND=noninteractive \
     ANIKOTO_CLI_REPO=${ANIKOTO_CLI} \
     ANIKOTO_CLI_BRANCH=${ANIKOTO_CLI_BRANCH} \
     ANI_CLI_WEB_REPO=${ANI_CLI_WEB} \
+    ANI_CLI_WEB_BRANCH=${ANI_CLI_WEB_BRANCH} \
     ANI_CLI_BIN=ani-cli \
     ANIKOTO_CLI_BIN=anikoto-cli \
     ANI_CLI_DOWNLOAD_DIR=/downloads \
@@ -57,7 +59,7 @@ RUN curl -fL "${YT_DLP_RELEASE_URL}" -o /usr/local/bin/yt-dlp \
     && chmod 0755 /usr/local/bin/yt-dlp \
     && yt-dlp --version
 
-RUN git clone --depth 1 "${ANI_CLI_WEB}" /app \
+RUN git clone --depth 1 --branch "${ANI_CLI_WEB_BRANCH}" "${ANI_CLI_WEB}" /app \
     && rm -rf /app/.git \
     && rm -f \
         /app/.dockerignore \