Hardens the families-comparison chart page (#107) so it is openable and legible on
real multi-year data. Two halves, both confined to the CLI render path (engine +
registry untouched, C14):
#108 — serve-time min-max decimation. A pure `decimate(ChartData, buckets)`
transform partitions the shared union-ts spine into <=~2000 buckets and emits each
series' per-bucket min+max (nulls preserved), bounding the served page to a few
thousand points regardless of the underlying M1 point count. Applied in emit_chart
on both the single-run and family paths; a no-op under budget (every existing
fixture). Full recorded data stays on disk; only the page is thinned. For a
walk-forward family the null-fill blow-up collapses for free (an all-null bucket
stays null). Deterministic (C1).
#102 — a run-context header. A `ChartMeta` (name/commit/window/broker/seed/taps,
+ member count for a family, + bound params for a single run) is built from the
RunManifest in build_chart_data / build_comparison_chart_data (which gain a `name`
arg), injected into window.AURA_TRACES.meta, and rendered by a new pure buildHeader
in chart-viewer.js (headless .mjs-guarded). The family window is the SPAN across
members (min from, max to), not the first member's window — the only reading that
labels a disjoint walk-forward family's true OOS coverage (it collapses to the
shared window for sweep/MC). Reuses the existing render_value for param display
(no new Scalar Display, keeping C7's tag-only param plane). The earlier
"manifest is NOT carried into the page" render pin is flipped to a positive one.
Verified: cargo test --workspace = 446 passed / 0 failed; cargo clippy --workspace
--all-targets -D warnings clean. New coverage: 5 decimate unit tests, single-run +
family meta wiring (incl. the span-window invariant), a buildHeader headless guard,
and two end-to-end cli_run tests pinning the served-page meta at the binary boundary.
closes#108closes#102
