feat(editor): Move code editor preferences to settings and add option to expand editor

Add global settings integration and persistent user preferences for
the code editor. Settings are now stored in localStorage and persist
across sessions.

Changes:
- Add theme, word wrap, minimap, line numbers, and font size settings
- Load editor preferences from localStorage on initialization
- Expose global openSettings function for cross-component access
- Add settingsInitialTab state to control which settings tab opens
- Pass initialTab prop to Settings component for navigation

This improves UX by remembering user preferences and allows other
components to open settings to specific tabs programmatically.

server/routes/git.js

@@ -502,16 +502,16 @@ router.post('/generate-commit-message', async (req, res) => {
  */
 async function generateCommitMessageWithAI(files, diffContext, provider, projectPath) {
   // Create the prompt
-  const prompt = `You are a git commit message generator. Based on the following file changes and diffs, generate a commit message in conventional commit format.
+  const prompt = `Generate a conventional commit message for these changes.
 
 REQUIREMENTS:
-- Use conventional commit format: type(scope): subject
-- Include a body that explains what changed and why
-- Valid types: feat, fix, docs, style, refactor, perf, test, build, ci, chore
-- Keep subject line under 50 characters
-- Wrap body at 72 characters
-- Be specific and descriptive
-- Return ONLY the commit message, nothing else - no markdown, no explanations, no code blocks
+- Format: type(scope): subject
+- Include body explaining what changed and why
+- Types: feat, fix, docs, style, refactor, perf, test, build, ci, chore
+- Subject under 50 chars, body wrapped at 72 chars
+- Focus on user-facing changes, not implementation details
+- Consider what's being added AND removed
+- Return ONLY the commit message (no markdown, explanations, or code blocks)
 
 FILES CHANGED:
 ${files.map(f => `- ${f}`).join('\n')}
@@ -519,7 +519,7 @@ ${files.map(f => `- ${f}`).join('\n')}
 DIFFS:
 ${diffContext.substring(0, 4000)}
 
-Generate the commit message now:`;
+Generate the commit message:`;
 
   try {
     // Create a simple writer that collects the response