fix(cli,tui): align CJK / wide-char markdown tables (#23863)

CJK and emoji glyphs render as two terminal cells but JS String#length
and the model's own padding count them as one, so any markdown table
with Chinese / Japanese / Korean cells drifts right per row when a
real terminal renders it. Both surfaces fix this with a display-cell
width measurement (wcswidth on the Python side, stringWidth on the
TUI side).

Changes:
- agent/markdown_tables.py: new helper. realign_markdown_tables(text)
  detects markdown table blocks (header + |---| divider) and
  rewrites the row padding using wcwidth.wcswidth so every pipe and
  dash lines up across rows. No-op on text without tables.
- cli.py: hook the helper into _render_final_assistant_content for
  strip / render modes (raw passes through untouched), and into the
  streaming line emitter so live token-by-token rendering also
  produces aligned tables. A small two-buffer state machine in
  _emit_stream_text holds table rows until the block ends, then
  flushes them through the realigner so all rows pad to a single
  per-column width.
- ui-tui/src/components/markdown.tsx: renderTable now uses
  stringWidth (Bun.stringWidth fast path + East-Asian-width-aware
  fallback, already memoised in @hermes/ink) instead of UTF-16
  String#length for both column-width measurement and per-cell
  padding. Drops the comment that documented the bug as a deliberate
  limitation.

Validation:
- New tests/agent/test_markdown_tables.py (11): every rebuilt block
  shares pipe column offsets across rows for pure CJK, mixed
  CJK+emoji, ragged-row, and multi-table inputs.
- Updated tests/cli/test_cli_markdown_rendering.py: the existing
  strip-mode test asserted exact whitespace; rewritten to assert the
  alignment contract (cell content survives + every rendered row
  shares pipe offsets).
- New ui-tui markdown.test.ts case (1): rendered column-2 start
  offset is identical for the header + every body row, including
  the CJK row that drifted before the fix.
- Live: hermes chat -q with the user-reported screenshot prompt now
  produces a perfectly aligned table on the wire (header, divider,
  4 body rows including '通义千问', all pipes at identical columns).

ui-tui/src/__tests__/markdown.test.ts

@@ -217,3 +217,50 @@ describe('Md wrapping', () => {
     expect(lines.some(line => line.startsWith(' hi  ok'))).toBe(true)
   })
 })
+
+describe('renderTable CJK width alignment', () => {
+  it('column starts share the same display offset across CJK rows', async () => {
+    const { stringWidth } = await import('@hermes/ink')
+
+    const md = [
+      '| 配置 | Config | 状态 |',
+      '|------|--------|------|',
+      '| Vicuna (report) | dense | × |',
+      '| ChatGLM | chat | ✓ |',
+      '| 通义千问 | qwen | × |'
+    ].join('\n')
+
+    // Pre-fix bug: ` `.repeat(w - stripInlineMarkup(...).length) used
+    // UTF-16 code units, so a CJK header cell padded to 2 cells while
+    // the body cell padded to 4, drifting subsequent columns by 2
+    // cells per CJK char.
+    //
+    // Post-fix contract: the prefix preceding the start of column N
+    // has the same display width across the header and every body row
+    // (deduped to skip the divider, which renders independently).
+    const lines = renderPlain(
+      React.createElement(Box, null, React.createElement(Md, { compact: true, t: DEFAULT_THEME, text: md }))
+    ).filter(line => line.trim().length > 0)
+
+    // Heuristic: a "data row" line either contains 'Config' (header)
+    // or one of the body labels; a divider is all box-drawing.  Use
+    // the substring 'Config' / 'dense' / 'chat' / 'qwen' as the
+    // unique anchor for column 2's start position on each row.
+    const colStarts = (line: string, anchor: string): number => {
+      const idx = line.indexOf(anchor)
+      return idx < 0 ? -1 : stringWidth(line.slice(0, idx))
+    }
+
+    const headerCol2 = lines.map(l => colStarts(l, 'Config')).find(v => v >= 0)
+    const denseCol2 = lines.map(l => colStarts(l, 'dense')).find(v => v >= 0)
+    const chatCol2 = lines.map(l => colStarts(l, 'chat')).find(v => v >= 0)
+    const qwenCol2 = lines.map(l => colStarts(l, 'qwen')).find(v => v >= 0)
+
+    expect(headerCol2).toBeDefined()
+    expect(denseCol2).toBe(headerCol2)
+    expect(chatCol2).toBe(headerCol2)
+    // The CJK row is the one that drifted before the fix.  It must
+    // align with the rest now.
+    expect(qwenCol2).toBe(headerCol2)
+  })
+})