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

src/App.css

@@ -114,3 +114,47 @@ button {
         background-color: #0f0f0f69;
     }
 }
+
+/* Collapsible tool output styling */
+details summary {
+    cursor: pointer;
+    user-select: none;
+}
+
+details summary::-webkit-details-marker {
+    display: none;
+}
+
+details[open] summary span:first-child {
+    transform: rotate(90deg);
+    display: inline-block;
+    transition: transform 0.2s ease;
+}
+
+details summary span:first-child {
+    transition: transform 0.2s ease;
+}
+
+/* Markdown body styling for dark theme */
+.markdown-body {
+    color: #ececec;
+}
+
+.markdown-body code {
+    background: #2f2f2f;
+    padding: 2px 6px;
+    border-radius: 3px;
+    font-family: monospace;
+}
+
+.markdown-body pre {
+    background: #1a1a1a;
+    padding: 12px;
+    border-radius: 6px;
+    overflow-x: auto;
+}
+
+.markdown-body pre code {
+    background: transparent;
+    padding: 0;
+}