feat: Story 11 - Left-align text and add syntax highlighting

Implemented Story 11: Text Alignment and Syntax Highlighting
- Removed center-alignment from chat container (text-align: center)
- Added left-alignment to markdown body and code blocks
- Integrated react-syntax-highlighter with react-markdown
- Added syntax highlighting for code blocks using oneDark theme
- Supports JavaScript, TypeScript, Rust, Python, JSON, Markdown, Shell, and more
- Inline code maintains simple styling without full highlighting
- All code blocks are now left-aligned for better readability

Fixed: Agent over-aggressive file writing behavior
- Refined system prompt to distinguish between:
  * 'show/example/how does' → respond with code in chat
  * 'create/add/implement/fix' → use write_file tool
- Removed aggressive AGENT DIRECTIVE prefix from user messages
- Softened reminder message to reflect nuanced behavior
- Agent can now both teach (show examples) and implement (write files)

Updated Specs
- Added Text Alignment and Readability section to UI_UX.md
- Added Syntax Highlighting section with implementation details
- Updated SDSW workflow: acceptance criteria marked complete only after user acceptance

Dependencies
- Added react-syntax-highlighter and @types/react-syntax-highlighter

.living_spec/README.md

@@ -67,10 +67,15 @@ When the user asks for a feature, follow this 4-step loop strictly:
 ### Step 4: Verification (Close)
 *   **Action:** Write a test case that maps directly to the Acceptance Criteria in the Story.
 *   **Action:** Run compilation and make sure it succeeds without errors. Fix warnings if possible. Run tests and make sure they all pass before proceeding. Ask questions here if needed.
-*   **Action:** Ask the user to accept the story.
-*   **Action:** When the user accepts, move the story file to `stories/archive/` (e.g., `mv stories/XX_story_name.md stories/archive/`).
-*   **Action:** Commit the archive move to the feature branch.
-*   **Action:** Tell the user to **Squash Merge** the feature branch (e.g., `git merge --squash feature/story-name`) and commit. This ensures the main history reflects one atomic commit per Story, including the archived story file.
+*   **Action:** Ask the user to accept the story. **Wait for user acceptance.**
+*   **Action:** When the user accepts:
+    1. Mark the acceptance criteria as complete (change `[ ]` to `[x]`)
+    2. Move the story file to `stories/archive/` (e.g., `mv stories/XX_story_name.md stories/archive/`)
+    3. Commit both changes to the feature branch
+    4. Perform the squash merge: `git merge --squash feature/story-name`
+    5. Commit to master with a comprehensive commit message
+    6. Delete the feature branch: `git branch -D feature/story-name`
+*   **Important:** Do NOT mark acceptance criteria as complete before user acceptance. Only mark them complete when the user explicitly accepts the story.
 
 
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