sec: hash tokens in DB, set Tauri CSP, escape quotes in XSS guard

- Session and email verification/reset tokens stored as SHA-256 hash in DB
  (raw token stays client-side in cookie/email link)
- Tauri CSP set: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';
  img-src 'self' data: https:; connect-src 'self' wss: https:
- escapeHtml now handles double and single quotes to prevent attribute-based XSS

web/src-tauri/tauri.conf.json

@@ -23,7 +23,7 @@
       }
     ],
     "security": {
-      "csp": null
+      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; connect-src 'self' wss: https:;"
     }
   },
   "bundle": {

web/src/components/MessageInput.tsx

@@ -155,7 +155,7 @@ function markdownToHtml(md: string): string {
 }
 
 function escapeHtml(s: string): string {
-  return s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
+  return s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&#039;");
 }
 
 function inlineMarkdownToHtml(text: string): string {