feat: add droid and opencode adapters with multi-agent examples

- Add droid adapter with exec subcommand support
- Add opencode adapter with run subcommand support
- Reorganize test files (streams.test.ts → output-streams.test.ts)
- Add multi-agent coordination examples
- Update adapter registry and tests
- Remove pack-config.ini
- Update documentation and metadata

Author: johnlindquist

.beads/beads.db

@@ -1,4 +1,5 @@
 {
   "database": "beads.db",
-  "jsonl_export": "issues.jsonl"
+  "jsonl_export": "issues.jsonl",
+  "last_bd_version": "0.27.0"
 }