v0.8.7 — Pipeline Diagrams, Semantic Seal & Pipeline Package

📦 Release

• Version sync to 0.8.7 (app + frontend + core): root pyproject.toml,
  frontend/ml-canvas/package.json / package-lock.json, and
  skyulf-core/setup.py bumped to 0.8.7.

🗺️ New — Mermaid pipeline diagrams, end to end

• Single source of truth in core: skyulf/pipeline/diagram.py renders a
  top-down flowchart TD (data -> preprocessing steps -> model) from
  config parts. Every label is double-quoted (mermaid rejects unquoted
  parentheses/brackets inside labels), with a human-readable head line and an
  optional second detail line — an explicit runtime summary or a compact
  digest of the step params (max 3 keys, _-prefixed/None/mapping values
  skipped, long values truncated). Algorithm names are humanized
  (random_forest_classifier → Random Forest Classifier); no internal
  node ids leak into labels.
• Core API surface: SkyulfPipeline.to_mermaid() and
  to_mermaid_markdown() plus mermaid_markdown() for fenced export;
  export_model_card()["diagram"] carries the same diagram; the notebook
  export cell renders a ## Pipeline topology fenced block using node
  display names, not uuids.
• Backend persistence: successful jobs now persist
  metrics.pipeline_diagram at completion, built from live node results —
  display names captured from the canvas (params._display_name →
  metadata["display_name"]), runtime summaries preferred with a
  params-digest fallback for nodes without one, model node typed from the
  job's model_type.
• Frontend: the Experiments "Pipeline Diagram" tab renders one card per
  selected run (legacy runs without a diagram are listed, not dropped), and
  each card has a Copy mermaid button that copies a ready-to-paste
  ```mermaid fenced block.
• Render hardening: mermaid's htmlLabels output is HTML, not XML — the
  rendered SVG is now parsed via DOMParser('text/html') and mounted with
  replaceChildren, fixing the browser "Opening and ending tag mismatch:
  br and p" error page; regression tests pin both the parse and the mount.
• Regression guards: core describe/humanize/fence tests, backend diagram
  adapter tests (display names, summaries, no-uuid assertions, notebook
  cell), and frontend real-mermaid parse tests plus copy-button tests.

🧠 Core — findings closeout

• F-07: to_native() converts engine frames back to pandas for
  interchange consumers.
• F-15: semantic fingerprint seals pipeline identity for reuse checks.
• F-19/F-19b: pipeline split into the skyulf/pipeline/ package —
  diagram generation extracted from the fit path, describe()/to_mermaid()
  live on the pipeline object.

🔧 Fixes & hardening

• Engine-agnostic node summaries: summary.py now handles both pandas
  and polars frames (shape, dtype breakdown, split renderings), pinned by
  tests/unit/test_summary_polars.py — previously polars-engine runs lost
  their diagram detail lines.
• Docs: pipeline_quickstart.md gained an "Inspecting a pipeline" section
  covering the diagram labels and export paths.

---