chart API: expose the remaining unchartable indicators (Renko, Correlation, PRS) so their docs pages can chart #498

Summary

Several indicator documentation pages on the Stock Indicators for .NET docs site cannot render an interactive <StockIndicatorChart> because the indicator has no entry in the chart API catalog (GET /indicators) and therefore no data endpoint. Please consider adding catalog listings + endpoints so these pages can show charts.

Context

• Docs consume @facioquo/indy-charts (Vue) + the chart API at charts-api.stockindicators.dev. (Was stock-charts-api.azurewebsites.net when this issue was filed; the backend moved to Cloudflare in feat: Migrate backend hosting from Azure to Cloudflare #539.)
• The component renders only indicators present in the catalog returned by GET /indicators (each needs a uiid, endpoint, chartType, parameters, results).
• Today the catalog has 83 indicators. The pages below map to indicators that are absent, so they're the only non-category pages with no chart.

Requested additions (by difficulty)

Straightforward — derived from an existing endpoint / single series:

• Gator Oscillator — derived from ALLIGATOR (jaw/teeth/lips). Two histograms (upper = |jaw − teeth|, lower = −|teeth − lips|), chartType: oscillator. Could reuse the ALLIGATOR calc/endpoint and expose upper/lower results, mirroring how BB exposes both BB (overlay) and BB-PCTB (oscillator). Implemented in feat: Add Gator, pivots, and quote transform overlays #499
• Heikin-Ashi — chartType: overlay (candlestick transform; open/high/low/close). Implemented in feat: Add candle line type for OHLC indicator results #535 + feat: Add Heikin-Ashi chart endpoint and catalog entry #536 (candle-rendered overlay that replaces the price candles); published in @facioquo/indy-charts@0.9.0.
• Renko — chartType: overlay (brick transform).
• Quote transforms (HL2, HLC3, OC2, OHL3, OHLC4 / "QuotePart") — chartType: overlay, a single derived price line. Implemented in feat: Add Gator, pivots, and quote transform overlays #499
• Pivot Points / Rolling Pivot Points — chartType: overlay (support/resistance levels). Partially implemented in feat: Add Gator, pivots, and quote transform overlays #499
• Williams Fractal "Pivots" — chartType: overlay (point markers; FRACTAL already exists, but the "Pivots" page has no listing). Implemented in feat: Add Gator, pivots, and quote transform overlays #499
• SMA analysis (MAD / MAPE / MSE) — chartType: oscillator (error metrics off an SMA). Re-implemented in feat: Split SMA analysis into per-metric chart listings #534 as per-metric listings (SMA-MAD / SMA-MAPE / SMA-MSE) after the original single-chart version was removed for mixed-unit unreadability; closes feat: SMA Analysis chart - split error metrics into separate depictions #475.

Needs a benchmark/second series (API shape question):

• Correlation Coefficient / R² and Price Relative Strength (PRS) — both require a comparison symbol. The current single-series endpoint shape doesn't express "indicator vs. benchmark," so these may need a new parameter (e.g. a second symbol) before they're chartable.

Pages currently chart-less for this reason

Renko, Correlation, Prs.

Originally also Gator, HeikinAshi, QuotePart, PivotPoints, RollingPivots, Pivots, and SmaAnalysis — all now charted via #499, #534, #535, and #536.

Consolidates (closed as duplicate of this issue):

• impl: Implement remaining indicators (Correlation, PRS, HeikinAshi, PivotPoints, Pivots, RollingPivots) #476 — its Pivot Points / Pivots / Rolling Pivots portion shipped in feat: Add Gator, pivots, and quote transform overlays #499 + feat: Pivot Points segments and price-channel layering #500; its remaining items (Correlation, PRS, Heikin-Ashi) are tracked above.

Notes

• For anything that's genuinely not chartable (e.g. needs a benchmark), a clear "not charted" decision is fine — this issue is to track which ones can be exposed.
• Once a listing exists, wiring the docs page is a one-line <StockIndicatorChart indicator="…" /> (plus a registry entry), so the docs side is cheap.