Make Free and Professional pricing buttons solid blue

All three pricing CTA buttons now share the same solid navy background,
white text, and blue hover state. Previously only anchor-element rules
existed for the solid variant; the button elements had no explicit
background so all three appeared unstyled.

dist/page_css.c

@@ -1903,7 +1903,11 @@ el_val_t page_css(void) {
         "      text-align: center;\n"
         "      padding: 0.875rem 1.5rem;\n"
         "      transition: background 300ms, opacity 300ms;\n"
+        "      background: var(--navy);\n"
+        "      color: #fff;\n"
+        "      box-shadow: 0 2px 16px rgba(0,82,160,.25);\n"
         "    }\n"
+        "    button.pricing-cta-navy:hover, button.pricing-cta-solid:hover, button.pricing-cta-ghost:hover { background: #0078D4; }\n"
         "    button[disabled] { opacity: 0.6; cursor: not-allowed; }\n"
         "\n"
     "  \n</style>"