⬆️ 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/random.md

@@ -0,0 +1,31 @@
+# `obistats.SampleIntWithoutReplacement` — Semantic Description
+
+The function **`SampleIntWithoutReplacement(n, max int) []int`** implements a *random sampling without replacement* algorithm over the integer range `[0, max)`.
+
+## Core Purpose  
+Generates **`n` distinct integers**, uniformly at random and *without repetition*, from the interval `[0, max)`.
+
+## Algorithmic Strategy  
+Uses an **incremental reservoir-like mapping** (`draw map[int]int`) to maintain uniqueness:
+- Iteratively draws `y = rand.Intn(max)` (i.e., uniform in `[0, max)`).
+- If `y` is already present (`ok = true`), it retrieves and reuses the stored value (a *swap trick*).
+- Then, `draw[y]` is set to the current upper bound (`max - 1`) and `max` decremented — effectively *removing* one value from the future draw space.
+- This preserves uniformity while avoiding collisions, in **O(n)** time and memory.
+
+## Key Properties  
+- ✅ Guarantees uniqueness: no duplicates in the returned slice.  
+- ⚖️ Uniform distribution over all possible `n`-element subsets of `[0, max)`.  
+- 🧠 Space-efficient: uses a map (O(n)) instead of shuffling an array of size `max`.  
+- 🚀 Efficient for large `max` and moderate `n`, where full-shuffle methods would be wasteful.
+
+## Return Value  
+A slice of length `n`, containing the sampled integers (order is *not* sorted or deterministic — reflects insertion order in `draw`).
+
+## Typical Use Cases  
+- Random subset selection (e.g., cross-validation folds, bootstrapping indices).  
+- shuffling without full permutation.  
+- Monte Carlo simulations requiring unique random IDs or positions.
+
+## Limitations / Notes  
+- Assumes `0 ≤ n ≤ max`; behavior is undefined otherwise.  
+- Relies on the global `math/rand` source (not seeded here); users should call `rand.Seed()` if reproducibility is needed.