fix(theme): stop inverting the home branding in dark mode

The previous commit made the home logo's fill theme-driven (`currentColor` +
`text-primary`) but left the pre-existing `dark:invert` in place. A CSS filter
does not care where the colour came from, so in dark mode a deployer's
configured primary is painted as its complement - with `primary: '#2dd4bf'` the
logo renders red - which defeats the customisation this PR documents. Thanks
@chatgpt-codex-connector for catching it.

The adjacent `<h1>` is included even though this PR did not introduce it: the two
are siblings in the same hero lockup and carry the same `text-primary
dark:invert`, so removing the inversion from only the logo would leave the mark
and the wordmark in complementary colours next to each other.

Verified with the reviewer's example value: both now compute rgb(43, 212, 189)
with `filter: none`, matching the configured #2dd4bf, where before the filter
painted them rgb(212, 43, 66).

Note this leaves ~30 other `text-primary dark:invert` pairs elsewhere in the
codebase untouched. They predate this PR and have the same conflict with a
customised theme, but they are outside the branding this change concerns.

Author: 2xburnt

src/pages/index.vue

@@ -49,7 +49,7 @@ const chainStore = useBlockchain();
           <g
             transform="translate(0.000000,132.000000) scale(0.100000,-0.100000)"
             :fill="chainStore.current?.themeColor || 'currentColor'"
-            class="text-primary dark:invert"
+            class="text-primary"
             stroke="none"
           >
             <path
@@ -75,7 +75,7 @@ const chainStore = useBlockchain();
           </g>
         </svg>
       </div>
-      <h1 class="text-primary dark:invert text-3xl md:!text-6xl font-bold">
+      <h1 class="text-primary text-3xl md:!text-6xl font-bold">
         {{ $t('pages.title') }}
       </h1>
     </div>