[cinar]

Fixes five indicators that differed from their published definitions, as found by the TA-Lib comparison in #536. Each now matches TA-Lib 0.8.3 on both reference datasets, and its skip: entry in internal/talibcompat is removed.

Commit	Issue	Change	First value
CCI	Fixes #521	Mean deviation measures every typical price in the window against the current SMA, not each bar's own SMA	bar 38 → 19
DPO	Fixes #522	Close[t−k] − SMA[t] instead of Close[t] − SMA[t−k]	bar 30 → 19
Ehlers Fisher	Fixes #523	Drops the extra * 0.5; Value1 is set to ±0.999 once it passes ±0.99	unchanged
Connors RSI	Fixes #524	Ranks the ROC against the 100 preceding values, not 99	bar 100 → 101
STC	Fixes #525	Exponential smoothing with factor 0.5 after each stochastic pass, instead of SMA(3)	bar 71 → 67

Review notes

• STC API change. The Stochastic and Apo fields are replaced by FastEma and SlowEma. NewStcWithPeriod keeps its signature; DPeriod now sets the smoothing factor 2 / (DPeriod + 1), so the default 3 gives Schaff's 0.5.
• STC MACD seeding. STC seeds the fast EMA on the slow EMA's first bar, as TA-Lib does. Macd and Apo start the fast EMA earlier (documented in Document smaller TA-Lib differences: EMA seeding, McGinley start, RVI name, VWAP window #535). Without this, STC still differed by about 1.5 points after 200 bars, because the stochastic magnifies small MACD differences. The doc comment notes the difference.
• Expected values come from TA-Lib. cci.csv, dpo.csv, ehlers_fisher.csv, connors_rsi.csv and the new stc.csv are regenerated from TA-Lib using each file's own inputs, rounded the way helper.RoundDigit rounds. The CCI example strategy's expected actions are regenerated from TA-Lib CCI.
• Ehlers Fisher hand-computed values. The previous values came from a Python reference with the same extra * 0.5. They are replaced with TA-Lib FISHER output, and a new test covers the clamp in both directions.
• DPO precision. The test compares at 4 digits, since one bar is exactly −4.195 and 2-digit rounding depends on floating-point error.
• STC tests. Adds the first STC test that checks values (against TA-Lib STC), plus a flat-input test.
• Adds the missing copyright header to trend/dpo_test.go.

Testing

fmt, vet, gosec, staticcheck, revive, go test -race over all packages, and gomarkdoc all pass. Coverage of the changed files is unchanged from before.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.81%. Comparing base (582c563) to head (c7f2b5d).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #537   +/-   ##
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  Coverage   91.80%   91.81%           
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  Files         240      240           
  Lines        7835     7843    +8     
=======================================
+ Hits         7193     7201    +8     
- Misses        549      550    +1     
+ Partials       93       92    -1     

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