chore: initialize the Go module and repository scaffolding

Add the Go module definition and lockfile, editor and ignore rules, and a Makefile with build, test, vet, install, and man targets. The version is injected at build time with -ldflags.

.gitignore

@@ -0,0 +1,21 @@
+# Binaries and build output
+/lazyntfy
+/dist/
+*.exe
+
+# Go test and coverage artifacts
+*.test
+*.out
+coverage.*
+
+# Local SQLite history (only when run with a repository-local path)
+*.db
+*.db-wal
+*.db-shm
+
+# Editors and operating systems
+.idea/
+.vscode/
+*.swp
+*~
+.DS_Store