refactor(devcontainer): expose gitconfig path via env var

Add GITCONFIG_PATH env variable and use it in volume mapping with default to $HOME/.gitconfig.
This allows custom gitconfig location for dev container.

Author: artdotlis

.devcontainer/dev.docker-compose.yml

@@ -18,10 +18,11 @@ services:
                 BIN_DEPLOY_REQ: ${BIN_DEPLOY_REQ}
                 SSH_AUTH_SOCK: /ssh-agent
                 BUN_BIN: ${BUN_BIN_R}
+                GITCONFIG_PATH: ${GITCONFIG_PATH}
         volumes:
             - ${SSH_AUTH_SOCK:-/dev/null}:/ssh-agent
             - .:/workspace
-            - ~/.gitconfig:/etc/gitconfig:ro
+            - ${GITCONFIG_PATH:-${HOME}/.gitconfig}:/etc/gitconfig:ro
         networks:
             - templrjs
             - ollama