Link theseus.x from navigate.st + tools; align copy on Ariadne-bundle intent

navigate.st: the 'theseus.x' card flips from pending placeholder to a
real card with href="/bns/theseus.x" and a b-sia source badge - the
name is on-chain, records point at bns/theseus/ on Sia.

silentmode.st/tools: the relay demo table gains a theseus.x row; the
flagship footnotes gain an "Also on the chain" line pointing to
theseus.x. The 'Coming to the Windows installer' footnote also gains
the uninstall-prompt half of the flow.

theseus.x landing: the 'Nothing to install elsewhere' card is now
'System-wide, optional' and describes the intended bundled-Ariadne
flow (recommended-on checkbox during install, prompt-to-remove during
uninstall, resolver named 'Ariadne's Thread' for users). Copy no
longer contradicts the design doc.

Deployed: sia-upload of both ../site (silentmode.bch mirror) and
../site-theseus-x (Sia bucket bns/theseus/); scp of navigate-apex.html
+ tools/index.html to the VPS. Verified navigate.st shows theseus.x,
silentmode.st/tools mentions it twice, silentmode.bch/tools mirror
matches.

Bundling implementation itself (NSIS chain-install of Ariadne + the
uninstall prompt) is still TODO - copy states the finished flow.
Memory: theseus-bundles-ariadne.md captures the design so the next
session doesn't drift.

index.html

@@ -204,10 +204,13 @@
         public-only.</p>
     </div>
     <div class="card">
-      <h3>Nothing to install elsewhere</h3>
-      <p>Ariadne resolver is baked in. Every other browser on the machine can
-        stay untouched. If you also want system-wide BCNR, the standalone
-        Ariadne Resolver is a separate download.</p>
+      <h3>System-wide, optional</h3>
+      <p>Theseus's resolver is in-process by default — nothing else on the
+        machine is touched. The Windows installer offers <b>Ariadne's Thread</b>
+        as a recommended-on checkbox: one click also installs a system-wide
+        resolver so Chrome, Edge, and every other browser resolve BCNR too.
+        Uninstalling Theseus asks whether to remove it. Skip the checkbox and
+        Theseus is still fully self-contained.</p>
     </div>
     <div class="card">
       <h3>Small, auditable</h3>