[FIX][18.0] theme*: fix website theme display error

[haumenphai]

before:

after:

I used a tool to convert theme preview from image file to svg, if you have the original .svg file that would be better.

odoo 18 requires a .svg file (representing the theme) to display to users when selecting on the website, but all current themes lack that file.
function reference:

@staticmethod
    def _process_svg(theme, colors, image_mapping):
        svg = None
        try:
            with tools.file_open(f'{theme}/static/description/{theme}.svg', 'r') as file:
                svg = file.read()
        except FileNotFoundError:
            return False

        default_colors = {
            'color1': '#3AADAA',
            'color2': '#7C6576',
            'color3': '#F6F6F6',
            'color4': '#FFFFFF',
            'color5': '#383E45',
            'menu': '#MENU_COLOR',
            'footer': '#FOOTER_COLOR',
        }
        color_mapping = {default_colors[color_key]: color_value for color_key, color_value in colors.items() if color_key in default_colors.keys()}

        # Replace the default colors by the chosen ones
        for default_color, chosen_color in color_mapping.items():
            svg = svg.replace(default_color, chosen_color)

        # Replace the default images by the one corresponding to the industry
        for default_img, new_img in image_mapping.items():
            svg = svg.replace(default_img, new_img)
        return svg

One more thing: Modules that are not website themes should not have the category "Theme" or "Theme/..."
because it will be displayed on the website when the user creates the website and reaches the selection step.

ref function:

 @api.model
    def configurator_recommended_themes(self, industry_id, palette, result_nbr_max=3):
        Module = request.env['ir.module.module']
        domain = Module.get_themes_domain()
        domain = AND([[('name', '!=', 'theme_default')], domain])
        client_themes = Module.search(domain).mapped('name')
        client_themes_img = {t: get_manifest(t).get('images_preview_theme', {}) for t in client_themes if get_manifest(t)}
        themes_suggested = self._website_api_rpc(
            '/api/website/2/configurator/recommended_themes/%s' % (industry_id if industry_id > 0 else ''),
            {
                'client_themes': client_themes_img,
                'result_nbr_max': result_nbr_max,
            }
        )
        process_svg = self.env['website.configurator.feature']._process_svg
        for theme in themes_suggested:
            theme['svg'] = process_svg(theme['name'], palette, theme.pop('image_urls'))
        return themes_suggested