* draw_text: adopt outer many_instances batch on linux/windows
CodeEditor opens an outer raster batch via DrawText::begin_many_instances
before its glyph loop. The linux/windows branch of DrawText::draw_text
ignored self.many_instances and opened its own nested batch, which
resolved (via find_appendable_drawcall) to the same draw_item whose
`instances` Vec was already swapped out by the outer open, panicking on
unwrap in Cx2d::begin_many_instances.
Mirror what the other platform branch (and draw_rasterized_glyphs_abs)
already do: take self.many_instances on entry, track whether the active
raster batch is the outer one, and hand it back on exit so the caller's
end_many_instances finalizes it. Skip the !drew_raster_this_frame area
clear when the outer batch is still live.
* Html/Markdown fixes: sub/superscript, table outlines/alignment, etc
- **Sub/sup in HTML**: added a `y_shift_scales` stack on `TextFlow`, composed onto `temp_y_shift` in `draw_text`. `<sub>` pushes `+0.55`, `<sup>` pushes `-0.2` in html.rs
- **Sub/sup in Markdown**: now handles `MdEvent::InlineHtml` for `<sub>`/`<sup>` (case-insensitive), using the same stacks.
- **Space after `&` (and other entities)**: the HTML lib's entity decoder now resets `last_non_whitespace` after truncate+push, so the whitespace-collapse check no longer drops the next real space.
- **Table column alignment (Markdown)**: `begin_table_cell` takes `align_x: f64`; tracks `Tag::Table` alignments and a per-row column index, passing each cell's `Alignment` through.
- **Table column alignment (HTML)**: `<td>`/`<th>` now honor `align="…"` and inline `style="text-align: …"` via new `cell_align_x` / `align_keyword_to_x` helpers in html.rs.
- **Per-row text alignment plumbing**: new `layout_align` field on `DrawText` is passed to the layouter, which already supports per-row alignment. `TextFlow` propagates a `cell_text_align_x` into it. This is the actual fix that makes cell alignment visible.
- **Wrap-flow alignment scaffolding**: implemented the previously-stubbed `Flow::Right { wrap: true }` branch in the turtle logic. Useful for non-text wrapping walks; text goes through the layouter path above.
- Add examples to uizoo: three new tables in both markdown and html tab -- a plain one, a left/center/right aligned one, and a numeric all-right-aligned one. They cover bold/italic/code/links/sub-sup/emoji/entities/strikethrough inside cells.
* minor cleanup; prefer `style` over `align` HTML tag
