⬆️ version bump to v4.5

- Update obioptions.Version from "Release 4.4.29" to "/v/ Release v5"
- Update version.txt from 4.29 → .30
(automated by Makefile)

autodoc/docmd/pkg/obistats/delta.md

@@ -0,0 +1,25 @@
+# Semantic Description of `obistats` Delta Testing Functionality
+
+This Go package (`obistats`) provides statistical tools for comparing performance metrics before and after code changes—typically used in benchmarking workflows.
+
+- **`DeltaTest` type**: A function signature for comparing two `*Metrics` instances (old vs. new), returning a *p*-value (`float64`) and an optional error.
+- **Purpose**: Determine whether two sets of samples likely originate from the same underlying distribution (i.e., detect significant performance regressions/improvements).
+
+## Supported Tests
+
+- **`NoDeltaTest()`**: A no-op test returning `(-1, nil)`, indicating *no statistical comparison* is performed.
+- **`TTest()`**: Performs a two-sample Welch’s *t*-test on `RValues`, assessing whether means differ significantly.
+- **`UTest()`**: Applies the Mann–Whitney *U* test (non-parametric), comparing distributions without assuming normality.
+
+## Common Errors
+
+- `ErrSamplesEqual`: All samples in one or both groups are identical.
+- `ErrSampleSize`: Insufficient data points for reliable testing (e.g., < 2).
+- `ErrZeroVariance`: One sample set has zero variance (no spread), breaking test assumptions.
+- `ErrMismatchedSamples`: Sample lengths differ (not used here but part of the broader API).
+
+## Design Rationale
+
+- Built on top of internal benchmarking infrastructure (see `github.com/golang-design/bench`).
+- Designed for modularity: callers can plug in different statistical tests as needed.
+- Returns *p*-values directly, enabling threshold-based decision logic (e.g., `if p < 0.05 → alert`).