fix(live): wrap preserves relative indent of multi-line picked elements

Companion to the prior outer-indent fix. live-wrap.mjs's
`originalLines.map(l => indent + '    ' + l.trimStart())` calls
`trimStart()` on every line, which strips ALL leading whitespace and
collapses multi-line picked elements to a uniform indent. So a 6/8/6
shape like

    <aside className="card">
      <h1 className="hero-title">Hero</h1>
    </aside>

was being reindented to 10/10/10 inside the wrapper, and on
accept/discard the round-trip restored 6/6/6 — the <h1> ended up at
its parent's depth instead of nested inside it.

Fix: extract `minLeadingSpaces(lines)` and strip only the COMMON
minimum across the picked lines before reindenting under the wrapper.
That mirrors how `deindentContent` on the accept side already works,
so wrap+accept now form a clean round-trip.

Test coverage:
- Expanded the indent regression test in live-accept.test.mjs to
  also assert the inner `<h1>` at 8-space indent and the closing
  `</aside>` at 6 — proving the relative depth survives wrap and
  discard end-to-end.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/live-accept.test.mjs

@@ -235,11 +235,17 @@ describe('live-accept — style-element edge cases', () => {
     runAccept(tmp, ['--id', 'INDENTDISC', '--discard']);
     const after = readFileSync(join(tmp, 'App.tsx'), 'utf-8');
     // The aside opener should land at exactly 6 spaces — same as the
-    // original. Any deeper indent is the bug Bugbot flagged. (Inner indent
-    // loss inside the element is a separate, pre-existing wrap behavior;
-    // not asserted here.)
+    // original — and the <h1> child at 8 (preserved relative depth).
+    // The earlier 6/6/6 collapse was caused by `originalLines.map(l =>
+    // indent + '    ' + l.trimStart())` in live-wrap stripping ALL
+    // leading whitespace before reindenting; the fix strips only the
+    // COMMON minimum so the relative structure is preserved.
     assert.match(after, /^      <aside className="card">$/m,
-      `<aside> opener must be at 6-space indent (was 8 before fix), got:\n${after}`);
+      `<aside> opener must be at 6-space indent (was 8 before outer-indent fix), got:\n${after}`);
+    assert.match(after, /^        <h1 className="hero-title">Hero<\/h1>$/m,
+      `<h1> child must be at 8-space indent — relative depth preserved through wrap+discard. Got:\n${after}`);
+    assert.match(after, /^      <\/aside>$/m,
+      `</aside> closer must be back at 6-space indent. Got:\n${after}`);
   });
 
   it('accept (no carbonize, raw HTML) restores at the original indent on JSX', () => {