fix: improve text contrast on HOME and DOWNLOADS nav links (#1609)

## Motivation

Follow-up to #1601 (downloads page contrast fix). The HOME and DOWNLOADS
navigation links in the top-right header use `text-exo-light-gray`
(`oklch(0.6 0 0)`) which is too dim against the dark header background.

## Changes

Changed both nav links in `HeaderNav.svelte` from `text-exo-light-gray`
to `text-white/70` for better visibility. Hover state
(`text-exo-yellow`) is unchanged.

## Why It Works

`text-white/70` provides noticeably better contrast against
`bg-exo-dark-gray` while still looking subdued relative to the yellow
accent color on hover. This is consistent with the approach used in
#1601.

## Test Plan

### Manual Testing
- Verified both links are clearly readable on the home page and
downloads page
- Hover state still transitions to yellow as expected

### Automated Testing
- Dashboard builds successfully

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

dashboard/src/lib/components/HeaderNav.svelte

@@ -95,7 +95,7 @@
     {#if showHome}
       <button
         onclick={handleHome}
-        class="text-sm text-exo-light-gray hover:text-exo-yellow transition-colors tracking-wider uppercase flex items-center gap-2 cursor-pointer"
+        class="text-sm text-white/70 hover:text-exo-yellow transition-colors tracking-wider uppercase flex items-center gap-2 cursor-pointer"
         title="Back to topology view"
       >
         <svg
@@ -116,7 +116,7 @@
     {/if}
     <a
       href="/#/downloads"
-      class="text-sm text-exo-light-gray hover:text-exo-yellow transition-colors tracking-wider uppercase flex items-center gap-2 cursor-pointer"
+      class="text-sm text-white/70 hover:text-exo-yellow transition-colors tracking-wider uppercase flex items-center gap-2 cursor-pointer"
       title="View downloads overview"
     >
       {#if downloadProgress}

nix/mlx.nix

@@ -41,7 +41,7 @@ let
 
   mlx = stdenv.mkDerivation rec {
     pname = "mlx";
-    version = let v = "0.30.7.dev20260224+5289547a"; in
+    version = let v = "0.30.7.dev20260220+13998a05"; in
       assert v == uvLockMlxVersion || throw "MLX version mismatch: nix/mlx.nix has ${v} but uv.lock has ${uvLockMlxVersion}. Update both the version and hash in nix/mlx.nix.";
       v;
     pyproject = true;
@@ -49,8 +49,8 @@ let
     src = fetchFromGitHub {
       owner = "rltakashige";
       repo = "mlx-jaccl-fix-small-recv";
-      rev = "5289547ada1cddda2b9716baf6a077a906d02189";
-      hash = "sha256-Zp9Jln7+Fpn79OfnIdiIVYzQDpih9lHrKtKJadh+c0I=";
+      rev = "13998a054715edcdc93618fb1496c79c7c25ff7c";
+      hash = "sha256-fAqA3hFwNBx7FcoGnhQsIFpAIRbC2EerACm4Fvne0Cc=";
     };
 
     patches = [

uv.lock

@@ -378,7 +378,7 @@ dependencies = [
     { name = "loguru", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "mflux", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "mlx", version = "0.30.6", source = { registry = "https://pypi.org/simple" }, extra = ["cpu"], marker = "sys_platform == 'linux'" },
-    { name = "mlx", version = "0.30.7.dev20260224+5289547a", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#5289547ada1cddda2b9716baf6a077a906d02189" }, marker = "sys_platform == 'darwin'" },
+    { name = "mlx", version = "0.30.7.dev20260220+13998a05", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#13998a054715edcdc93618fb1496c79c7c25ff7c" }, marker = "sys_platform == 'darwin'" },
     { name = "mlx-lm", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "msgspec", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "openai-harmony", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
@@ -1025,7 +1025,7 @@ dependencies = [
     { name = "huggingface-hub", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "matplotlib", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "mlx", version = "0.30.6", source = { registry = "https://pypi.org/simple" }, extra = ["cuda13"], marker = "sys_platform == 'linux'" },
-    { name = "mlx", version = "0.30.7.dev20260224+5289547a", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#5289547ada1cddda2b9716baf6a077a906d02189" }, marker = "sys_platform == 'darwin'" },
+    { name = "mlx", version = "0.30.7.dev20260220+13998a05", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#13998a054715edcdc93618fb1496c79c7c25ff7c" }, marker = "sys_platform == 'darwin'" },
     { name = "numpy", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "opencv-python", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "piexif", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
@@ -1072,8 +1072,8 @@ cuda13 = [
 
 [[package]]
 name = "mlx"
-version = "0.30.7.dev20260224+5289547a"
-source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#5289547ada1cddda2b9716baf6a077a906d02189" }
+version = "0.30.7.dev20260220+13998a05"
+source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#13998a054715edcdc93618fb1496c79c7c25ff7c" }
 resolution-markers = [
     "sys_platform == 'darwin'",
 ]
@@ -1108,7 +1108,7 @@ version = "0.30.7"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "jinja2", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
-    { name = "mlx", version = "0.30.7.dev20260224+5289547a", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#5289547ada1cddda2b9716baf6a077a906d02189" }, marker = "sys_platform == 'darwin'" },
+    { name = "mlx", version = "0.30.7.dev20260220+13998a05", source = { git = "https://github.com/rltakashige/mlx-jaccl-fix-small-recv.git?branch=address-rdma-gpu-locks#13998a054715edcdc93618fb1496c79c7c25ff7c" }, marker = "sys_platform == 'darwin'" },
     { name = "numpy", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "protobuf", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },
     { name = "pyyaml", marker = "sys_platform == 'darwin' or sys_platform == 'linux'" },