2.3.0

Two P0 fixes, six new recipes, a meaningful lint-noise reduction,
and figure-embedding adapters for Plotly / Matplotlib / HTML. All
changes are additive; no existing API was removed.

P0 fixes

- ``render_slide_thumbnails`` no longer silently drops slides 2..N
  on stock LibreOffice 7+ (whose ``--convert-to png`` filter only
  emits the first slide).  When the PNG path under-produces, the
  renderer transparently falls back to ``--convert-to pdf`` plus a
  per-page split via ``pdftoppm`` (Poppler) or ``pypdfium2``.  New
  ``strategy="auto" | "png" | "pdf"`` and ``dpi=`` knobs.
- ``SlideAnimations.add(kind, preset, shape, **kwargs)`` is now a
  documented entry point — the class was publicly exported but had
  no polymorphic ``add()`` method, leaving data-driven callers to
  build their own dispatcher.

API ergonomics

• MotionPath.svg(slide, shape, "M 0 0 H 100 V 100", viewbox=...)
  accepts standard SVG path syntax (M/m L/l H/h V/v C/c Q/q Z/z) and
  maps coordinates into OOXML's unit-square space. MotionPath.custom
  remains the OOXML-syntax escape hatch.
• kpi_slide delta auto-detects fraction-vs-raw: 0.27 →
  +27%, 14.0 → +14.0 (was silently +1400%). String
  delta and the new delta_text field pass through verbatim.
• quote_slide strips a leading hyphen / en-dash / em-dash from
  attribution so callers who already wrote "— Person" don't
  get "— — Person".
• Every recipe docstring now lists the palette / typography /
  shadow / radii slots it consumes — no more grepping the source.

Six new recipes

- ``section_divider`` — full-bleed cover with an optional eyebrow
  caption and ``progress=(3, 7)`` row of progress dots.
- ``chart_slide`` — line / line_markers / bar / column / pie /
  doughnut / area, with ``chart_palette=`` (named preset, colour
  list, or token-derived in palette priority order), plus
  ``legend=`` / ``smooth=`` / ``data_labels=`` toggles.
- ``table_slide`` — header band + banded rows; ``widths=`` (fractions
  or absolute Lengths), per-column ``aligns=``, optional
  ``totals=`` footer row.
- ``code_slide`` — monospace panel with optional Pygments syntax
  highlighting.
- ``timeline_slide`` — horizontal rail with alternating-side
  date / label pairs and ``done`` marker tinting.
- ``comparison_slide`` — matched two-column L/R rows.
- ``figure_slide`` — embed a Plotly Figure, Matplotlib Figure, SVG
  blob, HTML snippet, or image path; dispatches by type.

Lint signal-to-noise

• Implicit name-prefix grouping: shapes named card.bg /
  card.label are auto-grouped under card so the linter
  treats the pair as one logical unit without per-shape tagging.
  shape.lint_group = "" opts a shape out of the implicit group.
• ShapeCollision kind="matched" reclassified ERROR → INFO.
  Identical bounds are almost always intentional layering (badge
  • number, button + label); the kind is preserved on the issue
    for callers who really want to filter on it.
• slide.lint(disable=["ShapeCollision"], min_severity="warning")
  filters issues at the lint level rather than after the fact.
• auto_fix() now also clamps shape size when the shape is
  larger than the slide — translation alone could never converge,
  so the previous fixer was a silent no-op for oversize shapes.
  Multiple OffSlide issues on the same shape coalesce into one fix.
• SlideLintReport.fingerprints() returns 12-char content
  digests suitable for CI baselining — re-runs after layout
  changes only surface newly-introduced issues.

Design system

- ``DesignTokens.from_preset("modern_light" | "modern_dark" |
  "corporate_navy" | "vibrant")`` ships ready-to-use token sets so
  callers don't have to invent a brand from scratch.
- ``tokens.with_overrides({"palette.primary": "#FF6600",
  "typography.heading.size": Pt(40)})`` layers dotted-path tweaks
  onto a base set without forking it.
- ``kpi_slide`` and ``code_slide`` now apply ``shadows.card`` and
  ``radii.md`` via a shared ``_apply_card_styling`` helper, so the
  card-style backdrops actually reflect the design system instead
  of relying on hard-coded defaults.

compose.from_spec

• Recipe dispatch: layouts kpi / chart / table / code /
  timeline / comparison / quote / image_hero /
  section_divider / figure / title_recipe /
  bullets_recipe route to the matching recipes function.
  Legacy placeholder layouts (title, bullets, two_column,
  …) keep working for branded-template flows.
• tokens spec key accepts presets, YAML paths, inline dicts, or
  {"preset": name, "overrides": {...}}.
• vars spec key + {{name}} interpolation across every
  string in the spec, including dotted paths into nested mappings.
  Unknown names raise rather than silently rendering as the
  literal placeholder.
• compose.from_yaml(path, vars={...}): direct YAML entry point.

Figure embedding

New ``power_pptx.design.figures`` module with optional-dep adapters:

- ``add_plotly_figure(slide, fig, ...)`` — renders via
  ``fig.to_image()`` (needs ``plotly + kaleido``); SVG when
  ``cairosvg`` is present, PNG otherwise.
- ``add_matplotlib_figure(slide, fig, ...)`` — renders via
  ``fig.savefig()`` (needs ``matplotlib``); same SVG / PNG split.
- ``add_svg_figure(slide, svg, ...)`` — wraps the existing
  ``add_svg_picture`` so every figure kind shares one entry shape.
- ``add_html_figure(slide, html, ...)`` — proxy for HTML
  embedding (PowerPoint has no native HTML surface): screenshots
  the rendered DOM via headless Chromium (needs ``playwright`` +
  ``playwright install chromium``).

Each adapter imports its dependency lazily and raises
``FigureBackendUnavailable`` (subclass of ``ImportError``) naming
the install command when the dep is missing.

Tooling
~~~~~~~

- New ``release-on-version-bump.yml`` workflow auto-creates a
  ``vX.Y.Z`` tag and a GitHub release when a merge to ``master``
  changes ``power_pptx.__version__`` to a value with no matching
  tag.  Chains into the existing ``publish.yml`` for PyPI upload.