⬆️ 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/taxid.md

@@ -0,0 +1,19 @@
+# `obitax` Package: Taxonomic Identifier Handling
+
+The `obitax` package provides a lightweight, type-safe abstraction for handling taxonomic identifiers (`Taxid`) in the OBITools4 ecosystem.
+
+- **`Taxid` type**: A pointer to a string, representing an opaque taxonomic ID (e.g., NCBI TaxID).
+- **`TaxidFactory`**: A factory for constructing `Taxid`s from strings or integers, enforcing validation and normalization.
+
+Key features:
+- **Code prefix enforcement**: `FromString` validates that the input string starts with a required taxonomy code (e.g., `"tx"`), returning an error otherwise.
+- **String parsing**: Automatically strips leading whitespace and extracts the suffix after `':'`.
+- **Alphabet filtering**: Uses an ASCII set to extract only valid characters (e.g., digits), ensuring clean, standardized IDs.
+- **String interning**: Internally uses `Innerize` (via `InnerString`) to deduplicate strings—improving memory efficiency and comparison speed.
+- **Type safety**: `Taxid` is a distinct type (not raw string), reducing misuse and enabling future extension.
+
+Supported conversions:
+- `FromString(string)`: Parses `"tx:12345"` → internalized `"12345"`.
+- `FromInt(int)`: Converts e.g., `12345` → internalized `"12345"`.
+
+Designed for high-performance pipelines where many taxonomic IDs are processed and reused.