Feat: add POSIX-lite bootstrap foundation

Commands/Local/Dev/backend.just

@@ -9,10 +9,14 @@ migrate-up:
 migrate-down:
 	cd '{{backend_dir}}' && go run ./cmd/migrate down
 
-# Reset all embedded database migrations and reapply from scratch.
+# Reset all embedded database migrations.
 migrate-reset:
 	cd '{{backend_dir}}' && go run ./cmd/migrate reset
 
+# Reset embedded database migrations and apply them again from scratch.
+migrate-rebuild:
+	cd '{{backend_dir}}' && go run ./cmd/migrate reset && go run ./cmd/migrate up
+
 # Show the embedded database migration status.
 migrate-status:
 	cd '{{backend_dir}}' && go run ./cmd/migrate status
@@ -20,7 +24,3 @@ migrate-status:
 # Format backend Go source files.
 fmt:
 	cd '{{backend_dir}}' && gofmt -w ./cmd ./db ./internal
-
-# Run backend test suite.
-test:
-	cd '{{backend_dir}}' && go test ./...

Commands/Test/backend.just

@@ -0,0 +1,11 @@
+project_root := justfile_directory()
+backend_dir := project_root + "/Backend"
+
+# Run the full backend test suite.
+[default]
+all:
+	cd '{{backend_dir}}' && go test ./...
+
+# Run the isolated POSIX bootstrap smoke test.
+posix-bootstrap:
+	cd '{{backend_dir}}' && go test ./internal/bootstrap -run TestEnsureBootstrapPOSIXSkeletonInitializesEmptyRoot -count=1 -v

Commands/Test/mod.just

@@ -0,0 +1 @@
+mod backend