chore: reorganize snippets into subdirectories

- move root gitignores into gitignores/ subdirectory
- add gitignores for dart, dotnet, go, gradle, java, jetbrains, maven, nextjs, node, sublimetext, vscode, windows, xcode
- add root .gitignore excluding .claude/settings.local.json
- add empty README.md and licences/ placeholders (Apache, MIT, Mozilla)

gitignores/Go.gitignore

@@ -0,0 +1,34 @@
+### Go
+
+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Code coverage profiles and other test artifacts
+*.out
+coverage.*
+*.coverprofile
+profile.cov
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file
+.env
+
+# Editor/IDE
+# .idea/
+# .vscode/