Import Melee matches exports, add tests and local podman stack

- Parse Melee matches exports (one round per file, byes, null GameWins);
  one import form detects matches vs standings exports. Re-importing a
  round replaces just that round and keeps entered decks.
- Per-player deck entry for sessions scored from matches.
- node:test suite with anonymised fixtures; lockfile.
- scripts/local.sh runs the compose stack under podman with its own
  .env.local, project name and volume.
- README and CLAUDE.md docs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.env.example

@@ -1,5 +1,6 @@
-# generate with: openssl rand -hex 32
+# generate with: openssl rand -hex 16
 DB_PASSWORD=
+# generate with: openssl rand -hex 32
 SECRET_KEY=
 # 10+ characters
 ADMIN_PASSWORD=