Tidy README for production

- Restructure sections and add collapsible details

- Update repo tree and production note

- Mark main as production-ready in context

.context.json

@@ -3,7 +3,8 @@
     "name": "Bashrc Dotfiles",
     "purpose": "Global and per-user bash prompt + banner with seasonal palettes and time/season emoji accents.",
     "repo_root": "/home/steffen/Bashrc",
-    "default_branch": "main"
+    "default_branch": "main",
+    "release_state": "main is production-ready"
   },
   "branches": {
     "main": {