Enhance validation tests for various indicators with external library comparisons

- Added detailed comments explaining the validation limitations for MMA and ZLEMA due to differences in algorithm implementations.
- Implemented validation tests for True Range against TALib and Tulip, ensuring directional agreement.
- Updated Ulcer Index validation to clarify differences in algorithmic approaches between QuanTAlib and Skender.
- Enhanced Ease of Movement tests to verify directional agreement with Tulip's EMV, noting differences in volume scaling.
- Expanded Klinger Volume Oscillator tests to validate against Skender and Tulip, focusing on directional agreement across multiple period configurations.
- Improved Negative Volume Index tests to compare percentage changes with Tulip, addressing differences in starting values.
- Updated Positive Volume Index tests to validate against Tulip, emphasizing percentage change comparisons.
- Enhanced Williams Accumulation/Distribution tests to verify directional agreement with Tulip, highlighting formula differences.

docs/release-notes/cci-warmup-period-migration.md

@@ -0,0 +1,50 @@
+# Release Note: CCI WarmupPeriod — Static to Instance Migration
+
+## Summary
+
+`Cci.WarmupPeriod` has been changed from a **static** property to an **instance** property.
+This allows each `Cci` instance to report the warmup period for its configured `period` parameter,
+rather than a single hard-coded default.
+
+## Breaking Change
+
+Code that previously accessed `Cci.WarmupPeriod` as a static member will no longer compile:
+
+```csharp
+// ❌ Before (no longer compiles)
+int warmup = Cci.WarmupPeriod;
+```
+
+## Migration
+
+### Option A — Use the instance property (recommended)
+
+```csharp
+var cci = new Cci(period: 14);
+int warmup = cci.WarmupPeriod; // returns 14
+```
+
+### Option B — Use the obsolete static accessor (temporary bridge)
+
+A static `DefaultWarmupPeriod` property has been added and marked `[Obsolete]` to ease migration:
+
+```csharp
+// ⚠️ Compiles with a warning; will be removed in a future major version.
+#pragma warning disable CS0618
+int warmup = Cci.DefaultWarmupPeriod; // returns 20 (the default period)
+#pragma warning restore CS0618
+```
+
+## Timeline
+
+| Milestone | Action |
+|-----------|--------|
+| Current release | `Cci.DefaultWarmupPeriod` available as `[Obsolete]` static bridge |
+| Next major version | `Cci.DefaultWarmupPeriod` will be removed |
+
+## Related Changes
+
+- **Ppo.Update(TSeries):** Fixed state synchronization — `_p_state = _state` is now
+  assigned after the batch loop, matching the pattern used in `Pmo.Update(TSeries)`.
+- **Ppo.Batch(ReadOnlySpan):** Added `fastPeriod >= slowPeriod` guard to match the
+  constructor validation, ensuring invalid parameter combinations are rejected early.