⬆️ 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/obitax/iterator.md

@@ -0,0 +1,31 @@
+# Semantic Description of `obitax` Package Functionalities
+
+The `obitax` package provides a robust iterator-based API for traversing taxonomic data structures in Go. Its core component is the `ITaxon` interface, which implements a lazy, concurrent-safe iterator over taxon instances (`*Taxon`). Key features include:
+
+- **Iterator Creation**: `ITaxon` can be instantiated via `NewITaxon()` or derived from collections:  
+  - `TaxonSet.Iterator()`, `TaxonSlice.Iterator()` (sorted), and `Taxonomy.nodes.Iterator()`  
+  - Goroutines feed taxa into a channel, enabling non-blocking iteration.
+
+- **Control Methods**:  
+  - `Next()` advances to the next taxon, returning success/failure.  
+  - `Get()` retrieves the current taxon (must follow a successful `Next`).  
+  - `Finished()` checks if iteration is complete.
+
+- **Channel Management**:  
+  - `Push(taxon)` sends a taxon into the iterator’s channel.  
+  - `Close()` terminates iteration by closing the source channel.
+
+- **Iterator Composition**:  
+  - `Split()`: creates a new iterator sharing the same source and termination status (useful for parallel consumption).  
+  - `Concat(...)`: merges multiple iterators sequentially into one.
+
+- **Metadata Enrichment**:  
+  - `AddMetadata(name, value)` wraps the iterator to inject metadata into each taxon via `SetMetadata`.
+
+- **Subtree Traversal**:  
+  - `ISubTaxonomy()` (on `*Taxon` or via `Taxonomy.ITaxon(taxid)`) performs a breadth-first traversal of descendant taxa, starting from the current taxon or given ID. It uses parent-child adjacency logic to expand the subtree incrementally.
+
+- **Consumption Utility**:  
+  - `Consume()` exhausts an iterator without processing (e.g., for side-effect-only pipelines).
+
+All iterators are designed to be composable, memory-efficient (via channels), and safe for concurrent use. The package integrates with `obiutils` to manage pipeline registration/unregistration during subtree expansion.