reextract-originals: run as subprocess to avoid OOM

The in-process approach loaded all 2015 Strava originals into the server
process memory, causing OOM kills. Now spawns `bincio reextract-originals`
as a child process; heavy work runs in an isolated Python interpreter that
exits when done, freeing all memory.

Also adds `bincio reextract-originals` as a standalone CLI command that
prints JSON-lines progress to stdout — useful for running directly on the
VPS via SSH for large backlogs.

bincio/cli.py

@@ -18,6 +18,7 @@ from bincio.import_.cli import import_group     # noqa: E402
 from bincio.serve.init_cmd import init          # noqa: E402
 from bincio.serve.cli import serve              # noqa: E402
 from bincio.dev import dev                      # noqa: E402
+from bincio.reextract_cmd import reextract_originals  # noqa: E402
 
 main.add_command(extract)
 main.add_command(render)
@@ -26,3 +27,4 @@ main.add_command(import_group)
 main.add_command(init)
 main.add_command(serve)
 main.add_command(dev)
+main.add_command(reextract_originals)