Add web frontend and Docker packaging

Frontend is a single page served from classpath resources with a JSON API
alongside it. Kept separate from the MCP tools because the consumers differ:
a model reads formatted text, a browser needs structures. Only the database
is shared.

The page has three views - catalog with edition details, copies, detected
facts with evidence and a filterable file list; script search with FTS5
snippets and a viewer; and a format breakdown. No build step, no CDN, no
dependencies; light and dark follow the system.

New `serve` command puts the frontend and MCP on one port, one process and
one database connection, which is also what the container runs. `mcp` alone
still works for a headless setup.

Docker is a two-stage build: JDK plus the Rex-EMoolator submodule to compile,
JRE for runtime. installDist rather than build, so check - and with it
verifyCoreVersion - is skipped and git is not needed in the image. The pinned
:core tag is extracted from gradle.properties at build time and passed in by
the entrypoint, otherwise copy.core_version would record "nieznana" and
derived-artifact invalidation would stop working. Properties go through
JAVA_OPTS because Gradle's launcher treats everything after the script name
as application arguments.

Compose mounts the collection read-only and keeps the database and script
cache in a named volume. The port is bound to loopback.

Not verified: the image itself does not build here, the Docker daemon is not
running on this machine. The launcher, JAVA_OPTS handling and resource
packaging were tested against the installDist output directly.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docker-entrypoint.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+# Launcher generowany przez Gradle traktuje wszystko po nazwie skryptu jako
+# argumenty aplikacji, więc właściwości JVM muszą iść przez JAVA_OPTS.
+set -e
+
+# wersja :core jest przypięta submodułem w czasie budowania obrazu; bez niej
+# copy.core_version zapisałoby "nieznana" i przestałoby działać unieważnianie
+# cache'u pochodnych po bumpie emulatora
+CORE_VERSION="${CORE_VERSION:-$(cat /app/core-version 2>/dev/null || echo nieznana)}"
+
+JAVA_OPTS="-Dfile.encoding=UTF-8 -Dcatalog.data=${CATALOG_DATA:-/data} -Dcatalog.coreVersion=${CORE_VERSION} ${JAVA_OPTS}"
+export JAVA_OPTS
+
+exec /app/bin/rex-catalog "$@"