fix(nodes): Details link opens full-screen on desktop (#823) (#824)

Closes #823

## What
Remove the `window.innerWidth <= 640` gate on the `directNode`
full-screen branch in `init()` so the 🔍 Details link works on desktop.

## Why
- #739 (`e6ace95`) gated full-screen to mobile so desktop **deep links**
would land on the split panel.
- But the same gate broke the **Details link** flow (#779/#785): the
click handler calls `init(app, pubkey)` directly. On desktop the gated
branch was skipped, the list re-rendered with `selectedKey = pubkey`,
and the side panel was already open → no visible change.
- Dropping the gate makes the directNode branch the single, unambiguous
path to full-screen for both the Details link and any deep link.

## Why the desktop split-panel UX is still preserved
Row clicks call `selectNode()`, which uses `history.replaceState` — no
`hashchange` event, no router re-init, no `directNode` set. Only the
Details link handler (which calls `init()` explicitly) and a fresh
deep-link load reach this branch.

## Repro / verify
1. Desktop, viewport > 640px, open `/#/nodes`.
2. Click a node row → split panel opens (unchanged).
3. Click 🔍 Details inside the panel → full-screen single-node view (was
broken; now works).
4. Back button / Escape → back to list view.
5. Paste `/#/nodes/{pubkey}` directly → full-screen on both desktop and
mobile.

## Tests
`node test-frontend-helpers.js` → 553 passed, 0 failed.

Co-authored-by: you <you@example.com>

public/nodes.js

@@ -318,8 +318,11 @@
   function init(app, routeParam) {
     directNode = routeParam || null;
 
-    if (directNode && window.innerWidth <= 640) {
-      // Full-screen single node view (mobile only)
+    if (directNode) {
+      // Full-screen single node view (desktop + mobile).
+      // Reached via the 🔍 Details link or a deep link to #/nodes/{pubkey}.
+      // Row clicks use history.replaceState (no hashchange → no re-init),
+      // so the split-panel UX on desktop is preserved.
       app.innerHTML = `<div class="node-fullscreen">
         <div class="node-full-header">
           <button class="detail-back-btn node-back-btn" id="nodeBackBtn" aria-label="Back to nodes">←</button>