initial: fdroidserver-ipfs image

Downstream of registry.gitlab.com/fdroid/docker-executable-fdroidserver:master,
patched for publishing F-Droid repos over IPFS:

  - install Debian ipfs-cid so fdroidserver populates ipfsCIDv1 on every
    package file (APKs, icons, screenshots), which fdroidclient with an
    IPFS-gateway mirror routes via CID natively
  - rehash.py wrapper that adds ipfsCIDv1 to entry["index"], renames the
    index to a content-addressed filename, and re-signs entry.jar after
    `fdroid update` — closes the cache-busting gap on the index file itself
  - entrypoint.sh chains rehash automatically after any `fdroid update`,
    so existing fdroid-via-docker wrappers need no changes

See SPEC.md for the rationale and Change 2's algorithm; README.md for
end-user usage.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

entrypoint.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# fdroidserver-ipfs entrypoint.
+#
+# Mirrors the upstream image's behavior — sources bsenv.sh, runs
+# ${fdroidserver}/fdroid with the given args — then automatically invokes
+# fdroidserver-ipfs-rehash after a successful `fdroid update` so callers
+# don't have to remember the second step.
+
+set -eu
+. /etc/profile.d/bsenv.sh
+
+GRADLE_USER_HOME="${home_vagrant}/.gradle" "${fdroidserver}/fdroid" "$@"
+
+# Auto-rehash after a successful update. We check every arg (not just $1)
+# so global flags before the subcommand (e.g. `-v update`) still trigger it.
+for arg in "$@"; do
+    if [ "$arg" = "update" ]; then
+        fdroidserver-ipfs-rehash
+        break
+    fi
+done