Migrate to templ: Convert all HTML templates to type-safe templ components

- Add templ dependency for type-safe HTML rendering
- Convert index.html, login.html, register.html, dashboard.html, admin.html, admin_profile.html, admin_library.html to .templ files
- Generate Go code with templ generate for compile-time safety
- Update server routes to use templ components with proper rendering
- Refactor JavaScript in dashboard to avoid backtick parsing conflicts
- Delete old HTML template files
- Clean up project by removing unnecessary files and binaries

internal/handlers/auth.go

@@ -141,8 +141,9 @@ func (h *AuthHandler) Register(c echo.Context) error {
 <script>
 localStorage.setItem('token', '%s');
 localStorage.setItem('user', JSON.stringify(%s));
+document.cookie = 'token=%s; path=/; max-age=86400';
 window.location.href = '/';
-</script>`, token, fmt.Sprintf(`{"id":"%s","email":"%s","username":"%s"}`, uuid.UUID(user.ID.Bytes).String(), user.Email, user.Username))
+</script>`, token, fmt.Sprintf(`{"id":"%s","email":"%s","username":"%s"}`, uuid.UUID(user.ID.Bytes).String(), user.Email, user.Username), token)
 		return c.HTML(http.StatusCreated, html)
 	}
 
@@ -237,8 +238,9 @@ func (h *AuthHandler) Login(c echo.Context) error {
 <script>
 localStorage.setItem('token', '%s');
 localStorage.setItem('user', JSON.stringify(%s));
+document.cookie = 'token=%s; path=/; max-age=86400';
 window.location.href = '/';
-</script>`, token, fmt.Sprintf(`{"id":"%s","email":"%s","username":"%s"}`, uuid.UUID(user.ID.Bytes).String(), user.Email, user.Username))
+</script>`, token, fmt.Sprintf(`{"id":"%s","email":"%s","username":"%s"}`, uuid.UUID(user.ID.Bytes).String(), user.Email, user.Username), token)
 		return c.HTML(http.StatusOK, html)
 	}