Add claude config and rework bash dotfile management

- Add claude stow package (settings.json, statusline-command.sh)
- Replace .bashrc stow with source-injection approach to avoid conflicts
  with tools like oh-my-bash that want to own ~/.bashrc
- Move all bash customizations into .bashrc.omb, sourced conditionally
- setup.sh now checks for existing source lines before appending

claude/.claude/settings.json

@@ -0,0 +1,12 @@
+{
+  "attribution": {
+    "commit": "",
+    "pr": ""
+  },
+  "model": "sonnet",
+  "alwaysThinkingEnabled": true,
+  "statusLine": {
+    "type": "command",
+    "command": "bash ~/.claude/statusline-command.sh"
+  }
+}