Add --dbip CLI flag to auto-download/update the DB-IP MMDB database.

Downloads the latest dbip-city-lite-YYYY-MM.mmdb.gz before starting the
server, skipping when the local database is current, falling back to the
previous month on 404, and removing older databases after an update.
Promotes httpx to a runtime dependency.

pyproject.toml

@@ -20,6 +20,7 @@ dependencies = [
     "fastapi-vue>=1.3.1",
     "fastapi[standard]>=0.141.1",
     "html5tagger>=2.0.0",
+    "httpx>=0.28.1",
     "kanta>=0.8.1",
     "markdown-it-py>=4.2.0",
     "maxminddb>=3.1.1",
@@ -35,9 +36,7 @@ pagerite = "pagerite.__main__:main"
 Repository = "https://git.zi.fi/LeoVasanko/pagerite"
 
 [dependency-groups]
-dev = [
-    "httpx>=0.28.1",
-]
+dev = []
 
 [tool.hatch.version]
 source = "vcs"