fix(smolmachines): consolidate virtiofs mounts to stay within libkrun limit

libkrun limits total mounts + port-mappings to 5. With all three
sidecar daemons active (egress, git-gate, supervise), the prior
layout used 3 mounts + 3 ports = 6, causing the VM to crash at boot
with krun_start_enter returned -22.

Merge the egress confdir and git-gate scripts into a single staging
directory mounted at /bot-bottle-data/ with egress/ and git-gate/
subdirectories, reducing to 2 mounts + 3 ports = 5. Also clean up
leftover VMs before creating new ones to handle interrupted teardowns.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile.sidecars

@@ -89,16 +89,19 @@ RUN mkdir -p \
       /git-gate/creds \
       /git \
       /run/supervise \
-      /home/mitmproxy/.mitmproxy
+      /home/mitmproxy/.mitmproxy \
+      /bot-bottle-data/egress \
+      /bot-bottle-data/git-gate
 
 # Static wrapper for the git-gate entrypoint. The per-bottle
 # entrypoint script is either:
 #   - docker-cp'd to /git-gate-entrypoint.sh (docker/macOS backends),
 #     which overwrites this wrapper; or
-#   - virtiofs-mounted at /etc/git-gate/entrypoint.sh (smolmachines),
-#     where this wrapper delegates to it at runtime.
+#   - virtiofs-mounted at /bot-bottle-data/git-gate/entrypoint.sh
+#     (smolmachines), where this wrapper delegates to it at runtime.
+#     Fallback to /etc/git-gate/ for backwards compatibility.
 # Either way sidecar_init.py calls `/bin/sh /git-gate-entrypoint.sh`.
-RUN printf '#!/bin/sh\nexec /etc/git-gate/entrypoint.sh "$@"\n' \
+RUN printf '#!/bin/sh\nif [ -x /bot-bottle-data/git-gate/entrypoint.sh ]; then\n  exec /bot-bottle-data/git-gate/entrypoint.sh "$@"\nfi\nexec /etc/git-gate/entrypoint.sh "$@"\n' \
       > /git-gate-entrypoint.sh \
     && chmod 755 /git-gate-entrypoint.sh