feat(cfo): add Chande Forecast Oscillator

100 * (close - LinReg(close, period)) / close. Positive when close
overshoots the linear forecast, negative when it undershoots. Holds
the previous value if the close is zero (percentage form undefined).
Single param period (default 14).

Touchpoints: cfo.rs + mod.rs + lib.rs re-export, PyCfo + __init__.py
+ test_new_indicators SCALAR + test_known_values linear reference,
CfoNode + index.d.ts/index.js + indicators.test.js factory + reference,
WasmCfo via scalar macro, scalar-fuzz target, README + CHANGELOG.

bindings/python/tests/test_new_indicators.py

@@ -52,6 +52,7 @@ SCALAR = [
     (ta.StochRSI, (14, 14)),
     (ta.PPO, (12, 26)),
     (ta.APO, (12, 26)),
+    (ta.CFO, (14,)),
     (ta.DPO, (20,)),
     (ta.Coppock, (14, 11, 10)),
     (ta.StdDev, (20,)),