feat: extract shared infrastructure from shared_lib

Phase 1-3 of decoupling plan:
- Shared DB, models, infrastructure, browser, config, utils
- Event infrastructure (domain_events outbox, bus, processor)
- Structured logging
- Generic container concept (container_type/container_id)
- Alembic migrations for all schema changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

editor/node_modules/scheduler/README.md

@@ -0,0 +1,9 @@
+# `scheduler`
+
+This is a package for cooperative scheduling in a browser environment. It is currently used internally by React, but we plan to make it more generic.
+
+The public API for this package is not yet finalized.
+
+### Thanks
+
+The React team thanks [Anton Podviaznikov](https://podviaznikov.com/) for donating the `scheduler` package name.