Initial commit: project setup and db package

- Project scaffolding: go.mod, Makefile, .golangci.yaml, doc.go
- README, ARCHITECTURE, PROJECT_PLAN, PROGRESS documentation
- db package: Open (WAL, FK, busy timeout, 0600 permissions),
  Migrate (sequential, transactional, idempotent),
  SchemaVersion, Snapshot (VACUUM INTO)
- 11 tests covering open, migrate, and snapshot

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

go.mod

@@ -0,0 +1,17 @@
+module git.wntrmute.dev/kyle/mcdsl
+
+go 1.25.7
+
+require modernc.org/sqlite v1.47.0
+
+require (
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/sys v0.42.0 // indirect
+	modernc.org/libc v1.70.0 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+)