⬆️ 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_obiphylo.md

@@ -0,0 +1,61 @@
+# `obiphylo` Package: Semantic Description
+
+The `obiphylo` package provides a minimal yet expressive data structure and utilities for representing **phylogenetic trees** in Go, prioritizing simplicity, extensibility, and interoperability with standard phylogenetic formats.
+
+## Core Type: `PhyloNode`
+
+Represents a node in a phylogenetic tree—either an operational taxonomic unit (leaf) or an internal branching point.
+
+### Public Fields
+- `Name string`: Optional identifier for the node (e.g., species name, OTU label). May be empty.
+- `Children map[*PhyloNode]float64`: Maps child nodes to their associated **branch lengths** (evolutionary distances). Supports `NaN` for unspecified or unmeasured branches.
+- `Attributes map[string]any`: A flexible key-value store for arbitrary metadata (e.g., bootstrap values, posterior probabilities, geographic origin). Values may be of any type.
+
+> ⚠️ *All fields are exported for direct read/write access, but users should prefer the provided methods to ensure consistency (e.g., `AddChild`, `SetAttribute`).*
+
+## Public Methods
+
+### Construction & Mutation
+- **`NewPhyloNode(name string) *PhyloNode`**  
+  Instantiates a new node with optional name. Initializes `Children` and `Attributes` as empty maps.
+
+- **`AddChild(child *PhyloNode, distance float64)`**  
+  Appends a child node to the current one with specified branch length. If `distance` is `NaN`, it is stored as-is (and omitted in Newick output).  
+  → *Enables incremental tree building from leaves to root.*
+
+- **`SetAttribute(key string, value any)`**  
+  Stores or updates a metadata entry on the node. Overwrites existing keys.
+
+- **`GetAttribute(key string) (any, bool)`**  
+  Retrieves a metadata value and reports presence via boolean. Returns zero `value` if key absent.
+
+### Tree Serialization
+- **`Newick(level int) string`**  
+  Recursively generates a Newick-formatted subtree rooted at the current node.  
+  - Nodes without children appear as `Name` (or empty string if unnamed).  
+  - Internal nodes are rendered with comma-separated children in parentheses.  
+  - Branch lengths (`:distance`) appear *only if finite* (i.e., `!math.IsNaN(distance)`).  
+  - Indentation (`level * "\t"`) improves human readability.  
+  - Root-level calls (e.g., `root.Newick(0)`) append a final semicolon (`;`).  
+  → *Designed for export to tools like RAxML, FigTree, or Iq-TREE.*
+
+## Design Principles
+
+- **Zero external dependencies**: Pure Go implementation.
+- **Idiomatic efficiency**: Child lookup via `map` ensures O(1) average access.
+- **Extensibility over rigidity**: Arbitrary metadata via `any` supports evolving annotation needs without API changes.
+- **Format compliance**: Newick output adheres to widely accepted syntax (with optional branch lengths), enabling seamless integration with phylogenetic software ecosystems.
+
+## Usage Example
+
+```go
+root := obiphylo.NewPhyloNode("Root")
+leafA := obiphylo.NewPhyloNode("Species_A")
+leafB := obiphylo.NewPhyloNode("Species_B")
+
+root.AddChild(leafA, 1.2)
+root.AddChild(leafB, math.NaN()) // distance omitted in output
+
+leafA.SetAttribute("bootstrap", 95)
+root.Newick(0) // → "\t(Species_A:1.2,Species_B);"
+```