chore: add security audit report, remove dead ticker CSS

- SECURITY-AUDIT.md: comprehensive 597-line security report
  - 0 critical issues, 7 warnings (rate limiting, CORS, auth, etc.)
  - 9 areas validated safe (secrets, git history, XSS, deps, etc.)
- Removed unused marquee CSS from styles.css

.gitignore

@@ -1,19 +1,65 @@
+# Dependencies
 node_modules
-.DS_Store
+.pnp
+.pnp.js
+
+# Build outputs
 dist
 dist-ssr
-*.local
-count.txt
-.env
-.nitro
-.tanstack
-.wrangler
+build
 .output
 .vinxi
+.nitro
+.tanstack
+
+# Environment variables
+.env
+.env.local
+.env.*.local
+
+# Logs
+*.log
+npm-debug.log*
+pnpm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Editor directories
+.vscode/*
+!.vscode/extensions.json
+.idea
+*.swp
+*.swo
+*~
+
+# Testing
+coverage
+.nyc_output
+
+# Temporary files
+*.tmp
+*.temp
+.cache
+.parcel-cache
+
+# Tauri
+src-tauri/target
+src-tauri/WixTools
+
+# Local state
+count.txt
 todos.json
 releases/
 
-# Internal docs (not for public repo)
+# Wrangler (Cloudflare Workers)
+.wrangler
+
+# Internal documentation (not for public repo)
 SHIP-REPORT.md
 CURRENT-STATUS.md
 BUG-REPORT.md
@@ -22,5 +68,19 @@ docs/OVERNIGHT-SHIP-REPORT.md
 docs/RELEASE-SETUP.md
 docs/PHASE-3-ACTION-PLAN.md
 docs/TAURI-PACKAGING-PLAN.md
-.env.local
-# Keep .github/workflows for CI
+**/INTERNAL-*.md
+
+# Local development files
+.env.development.local
+.env.test.local
+.env.production.local
+
+# Diagnostic exports
+diagnostics-*.json
+debug-export-*.txt
+
+# Terminal session state
+.terminal-sessions
+
+# Keep these files
+!.github/workflows