P3 sweep fixes: snap-row CSS, tree expand, --no-ownership drop, target path

Bug fixes from the Playwright sweep against the live smoke server:

1. Snapshot-picker layout. The .snap-row class was used in the wireframe
   but never landed in web/styles/input.css; rows rendered as vertical
   blocks instead of a 6-column grid. Added the token (mirrors host-row
   shape with restore-specific column widths).

2. Tree expansion. hx-target='closest .tree-row + .tree-children' isn't
   a valid HTMX selector — modifiers don't chain. Replaced HTMX-driven
   expansion with a small window.__rmTreeToggle helper that uses plain
   fetch + .tree-pair wrapper structure for trivial sibling lookup.
   Caches loaded state per node.

3. --no-ownership flag dropped. Restic 0.17 introduced --no-ownership;
   0.16 rejects it ('unknown flag') before doing any work. Since the
   agent runs as root in the systemd unit, restored files keep their
   original uid/gid either way and the parent dir is root-owned, so
   the 'cp without sudo' rationale doesn't hold. Drop the flag entirely.

4. Default target dir moved to /var/lib/restic-manager/restore. The
   systemd unit pins ReadWritePaths to /etc/restic-manager +
   /var/lib/restic-manager (with ProtectSystem=strict making the rest
   of /var read-only); writes to /var/restic-restore failed with
   'read-only file system'.

5. Confirm summary HTML escaping. defaultTarget JS literal evaluates
   to a string with literal angle brackets; insertion into innerHTML
   must escape them. Added an inline HTML-escape pass.

tasks.md ticked for the Restore sub-phase with a sweep summary
covering the live end-to-end test.

web/styles/input.css

@@ -206,6 +206,25 @@
   .src-row.clickable > .row-link { pointer-events: auto; }
   .src-row.clickable > .row-action { pointer-events: auto; }
 
+  /* ---------- snapshot picker rows (Restore wizard step 1) ---------- */
+  .snap-row {
+    display: grid; align-items: center;
+    grid-template-columns: 150px 130px 1fr 90px 130px 80px;
+    column-gap: 16px;
+    padding: 11px 14px; font-size: 13px;
+    border-bottom: 1px solid var(--line-soft);
+    cursor: pointer;
+    transition: background 100ms ease;
+  }
+  .snap-row:last-child { border-bottom: 0; }
+  .snap-row:hover { background: var(--panel-hi); }
+  .snap-row.head {
+    font-size: 11px; color: var(--ink-fade);
+    text-transform: uppercase; letter-spacing: 0.08em;
+    padding-top: 9px; padding-bottom: 9px; cursor: default;
+  }
+  .snap-row.head:hover { background: transparent; }
+
   /* ---------- schedule rows (Schedules tab) ---------- */
   .schd-row {
     display: grid; align-items: center;