feat: Add tool categories for organization

- Add category field to Tool dataclass (Text, Developer, Data, Other)
- Display tools grouped by category in main UI with section headers
- Add category dropdown selector in tool builder dialog
- Update example tools with appropriate categories
- Document category feature in README

Categories help organize tools in the UI for easier navigation.
Tools without a category default to "Other".

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

README.md

@@ -204,6 +204,7 @@ A tool is a YAML config file in `~/.smarttools/<name>/config.yaml`:
 ```yaml
 name: summarize
 description: Condense documents to key points
+category: Text  # Optional: Text, Developer, Data, or Other
 arguments:
   - flag: --length
     variable: length
@@ -219,6 +220,17 @@ steps:
 output: "{response}"
 ```
 
+### Categories
+
+Tools can be organized into categories for easier navigation in the UI:
+
+| Category | Description |
+|----------|-------------|
+| `Text` | Text processing (summarize, translate, grammar) |
+| `Developer` | Dev tools (explain-error, gen-tests, commit-msg) |
+| `Data` | Data extraction and conversion (json-extract, csv) |
+| `Other` | Default for uncategorized tools |
+
 ### Multi-Step Tools
 
 Chain AI prompts with Python code for powerful workflows: