refactor(theme): remove dynamic styling systems and migrate to static CSS architecture

This commit introduces a major internal refactor of the theme, replacing all
dynamic styling mechanisms with a fully static, CSS-based system.

The previous implementation relied on WordPress Customizer settings, PHP-based
style generation, and inline CSS injection for fonts, colors, and header behavior.
These systems have been completely removed and replaced with a deterministic
architecture using CSS variables and dedicated stylesheets.

Key changes:
- Removed dynamic font system (Google/local/inline CSS)
- Removed dynamic color system and Customizer controls
- Removed legacy compatibility layer (legacy-aliases.php)
- Removed custom header support and related UI (header image, text color)
- Eliminated inline <style> injection in wp_head
- Introduced static typography system via fonts.css
- Introduced static color system via colors.css
- Refactored style.css to rely entirely on CSS variables
- Cleaned up conflicting font declarations and redundant rules
- Simplified theme structure and reduced PHP overhead
- Aligned translation template with theme slug (zeitfresser.pot)

Result:
- Improved frontend performance and caching behavior
- Reduced PHP execution and complexity
- Fully deterministic rendering without runtime style mutations
- Cleaner, more maintainable codebase

No visual changes intended.

languages/zeitfresser.pot

@@ -2,8 +2,8 @@
 # This file is distributed under the GNU General Public License v2 or later.
 msgid ""
 msgstr ""
-"Project-Id-Version: Daisy Blog 1.0.0\n"
-"Report-Msgid-Bugs-To: https://wordpress.org/support/theme/daisy-blog\n"
+"Project-Id-Version: Zeitfresser Theme"
+"Report-Msgid-Bugs-To: https://github.com/Domoel/Zeitfresser-Wordpress-Theme"
 "POT-Creation-Date: 2023-04-10 14:33:31+00:00\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
@@ -847,7 +847,7 @@ msgid "Daisy Blog"
 msgstr ""
 
 #. Theme URI of the plugin/theme
-msgid "https://graphthemes.com/daisy-blog"
+msgid "https://github.com/Domoel/Zeitfresser-Wordpress-Theme"
 msgstr ""
 
 #. Description of the plugin/theme