feat: Story 8 - Collapsible tool outputs + autonomous coding improvements

Implemented Story 8: Collapsible Tool Outputs
- Tool outputs now render in <details>/<summary> elements, collapsed by default
- Summary shows tool name with key argument (e.g., ▶ read_file(src/main.rs))
- Added arrow rotation animation and scrollable content (max 300px)
- Enhanced tool_calls display to show arguments inline
- Added CSS styling for dark theme consistency

Fixed: LLM autonomous coding behavior
- Strengthened system prompt with explicit examples and directives
- Implemented triple-reinforcement system (primary prompt + reminder + message prefixes)
- Improved tool descriptions to be more explicit and action-oriented
- Increased MAX_TURNS from 10 to 30 for complex agentic workflows
- Added debug logging for Ollama requests/responses
- Result: GPT-OSS (gpt-oss:20b) now successfully uses write_file autonomously

Documentation improvements
- Created MODEL_SELECTION.md guide with recommendations
- Updated PERSONA.md spec to emphasize autonomous agent behavior
- Updated UI_UX.md spec with collapsible tool output requirements
- Updated SDSW workflow: LLM archives stories and performs squash merge

Cleanup
- Removed unused ToolTester.tsx component

.living_spec/stories/archive/08_collapsible_tool_outputs.md

@@ -0,0 +1,25 @@
+# Story: Collapsible Tool Outputs
+
+## User Story
+**As a** User
+**I want** tool outputs (like long file contents or search results) to be collapsed by default
+**So that** the chat history remains readable and I can focus on the Agent's reasoning.
+
+## Acceptance Criteria
+*   [x] Frontend: Render tool outputs inside a `<details>` / `<summary>` component (or custom equivalent).
+*   [x] Frontend: Default state should be **Closed/Collapsed**.
+*   [x] Frontend: The summary line should show the Tool Name + minimal args (e.g., "▶ read_file(src/main.rs)").
+*   [x] Frontend: Clicking the arrow/summary expands to show the full output.
+
+## Out of Scope
+*   Complex syntax highlighting for tool outputs (plain text/pre is fine).
+
+## Implementation Plan
+1. Create a reusable component for displaying tool outputs with collapsible functionality
+2. Update the chat message rendering logic to use this component for tool outputs
+3. Ensure the summary line displays tool name and minimal arguments
+4. Verify that the component maintains proper styling and readability
+5. Test expand/collapse functionality across different tool output types
+
+## Related Functional Specs
+*   Functional Spec: Tool Outputs