feat(docker-watcher): phase 1 - project scaffold & SQLite store

Initialize Go module, directory structure, and full SQLite store layer:
- 7-table schema (projects, stages, registries, settings, instances,
  deploys, deploy_logs) with auto-migration
- CRUD operations for all entities with proper error handling
- ErrNotFound sentinel for distinguishing 404 from 500 in handlers
- WAL mode, foreign keys, busy timeout pragmas

go.mod

@@ -0,0 +1,11 @@
+module github.com/alexei/docker-watcher
+
+go 1.23
+
+require (
+	github.com/go-chi/chi/v5 v5.2.1
+	github.com/google/uuid v1.6.0
+	github.com/robfig/cron/v3 v3.0.1
+	gopkg.in/yaml.v3 v3.0.1
+	modernc.org/sqlite v1.34.5
+)