Combine opencode-container and claude-container into a unified agent-container

Merge the two separate container projects into a single image and
management script. Both OpenCode and Claude Code are installed in the
same Arch Linux image and share one persistent $HOME directory, which
enables the opencode-claude-bridge plugin to read Claude CLI credentials
from within OpenCode.

Subcommands: opencode, claude, update, force-cleanup.

agent.aliases

@@ -0,0 +1,17 @@
+if [ -n "$BASH_VERSION" ]; then
+    AGENT_CONTAINER_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+elif [ -n "$ZSH_VERSION" ]; then
+    AGENT_CONTAINER_DIR="${0:A:h}"
+fi
+
+opencode() {
+    python3 "$AGENT_CONTAINER_DIR/agent-container.py" opencode "$@"
+}
+
+claude() {
+    python3 "$AGENT_CONTAINER_DIR/agent-container.py" claude "$@"
+}
+
+agent-container() {
+    python3 "$AGENT_CONTAINER_DIR/agent-container.py" "$@"
+}