feat: charts and shape primitives + XML parser (full design, 5 phases)

[RoboNET]

Implements the complete charts-and-shapes design — all 5 phases — so LLM agents can generate polished graphics and charts from declarative templates without hand-written SVG.

Design spec: docs/superpowers/specs/2026-06-12-charts-and-shapes-design.md. Each phase has its own TDD plan under docs/superpowers/plans/.

Phase 1 — Shape primitives

• Box shapes rect/circle/ellipse (fill/gradient/stroke/opacity, rect radius, circle size shorthand).
• Gradient fill object ({gradient: linear|radial, colors, angle}) → reuses the existing CSS gradient renderer.
• draw element — free-form absolute-coordinate shapes: line, polyline, rect, circle, path (M/L/Q/C/Z, hand-written AOT-safe tokenizer, no regex). ResourceLimits.MaxShapesPerDraw.

Phase 2 — Charts base

• chart element: bar (vertical/horizontal/stacked), line/area (smooth curves, point markers), pie/donut (slice % / value labels).
• Themes (light/dark/minimal) + palettes (ocean/sunset/forest/mono/vivid or explicit colors) — beautiful by default, zero styling decisions required.
• Nice-tick axis math, grid, legend, title, "no data" placeholder. Series data binds from the data context like table rows (data: "{{ sales }}").

Phase 3 — Charts extension

• scatter/bubble ([x,y] / [x,y,r] tuple data, X+Y axis scaling, radius-normalized bubbles), gauge (270° dial), progress (ring), sparkline (chrome-free inline line).

Phase 4 — Charts advanced

• heatmap (2D grid, value→color scale, x/y labels, cell values), radar (category spokes, per-series filled polygons, concentric rings).

Phase 5 — FlexRender.Xml

• New package: an alternative XML template syntax producing the same AST as YAML (LLMs emit XML attributes more reliably than YAML indentation). XmlTemplateParser translates XML → the shared ParseDocumentRoot, reusing all element/chart/shape parsing, KnownProperties validation + typo suggestions, and resource limits. RenderXml extension. Docs: docs/wiki/Xml-Syntax.md.

Quality

• 3303 tests, 0 failures; build 0 errors. ~250 new tests + golden snapshots for every shape and chart type (visually verified).
• AOT-safe throughout (no reflection/dynamic/runtime-regex; XDocument not XmlSerializer). Sealed classes, ArgumentNullException.ThrowIfNull, switch-based dispatch, XML docs on public API.
• Hardened for untrusted LLM input: non-finite/non-numeric/over-limit data rejected on both inline and data-bound paths; tuple arity validated; degenerate geometry (empty series, single point, <3 radar categories, identical min/max) never crashes/NaNs/divides-by-zero; malformed XML and malformed <else-if> rejected with clear errors.
• Resource limits added (MaxShapesPerDraw, MaxSeriesPerChart, MaxDataPointsPerSeries), never weakened.
• A final holistic cross-cutting review gated merge on one real defect (data-bound series bypassing MaxDataPointsPerSeries), now fixed.

Docs

llms.txt, llms-full.txt, wiki Element-Reference/Visual-Reference/Xml-Syntax (with rendered examples under examples/visual-docs/), Playground JSON schema + autocomplete, AGENTS.md package structure.

Follow-ups (tracked in the phase plans)

• Update flexrender/skills/template/SKILL.md in RoboNET/FlexRender-Marketplace.
• Inner draw-shape & chart-series property typo validation; expression-bound scatter/bubble tuple data; MaxPathCommands as a configurable limit.

🤖 Generated with Claude Code

[RoboNET]

Follow-up refactor: decouple FlexRender.Xml from FlexRender.Yaml

Per review feedback ("why does the XML parser depend on YAML? they should be independent"), FlexRender.Xml now depends only on FlexRender.Core — no FlexRender.Yaml, no YamlDotNet.

What changed (6 commits, 58cc825..202244e):

• New format-neutral node model in Core: TemplateMapping / TemplateSequence / TemplateScalar (FlexRender.Parsing.Nodes, zero external deps).
• The shared parsing engine moved into Core (Parsing/Engine/): TemplateEngine.ParseDocumentRoot(TemplateMapping) + ElementParsers, ChartParsers, ShapeParsers, KnownProperties, NodePropertyHelpers — retyped from the YamlDotNet DOM onto the neutral model.
• FlexRender.Yaml is now a thin facade: YamlDotNet → YamlNodeConverter → Core engine. Public API (TemplateParser) unchanged.
• FlexRender.Xml converts XDocument → XmlNodeConverter → the same Core engine. Dropped the FlexRender.Yaml project reference and the old XmlToYamlNodeConverter.
• Dropped the now-unneeded InternalsVisibleTo("FlexRender.Xml") from Yaml; updated AGENTS.md + llms.txt.

Result: both format packages share one engine in Core and neither depends on the other. YamlDotNet stays confined to FlexRender.Yaml.

Verification: full suite green on net10.0 — 3311 passed, 0 failed (3060 main + 164 ImageSharp + 87 CLI). Build clean (0 errors). XML produces the identical Template AST as before (XmlYamlEquivalence tests pass).