⬆️ 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/obiutils/download.md

@@ -0,0 +1,37 @@
+## `obiutils.DownloadFile` — Semantic Feature Overview
+
+- **Core Functionality**: Downloads a file from a given URL to a specified local path.
+  
+- **HTTP Client Behavior**:
+  - Uses `http.Get()` for simple, synchronous GET requests.
+  - Validates the HTTP status code; aborts on non-200 responses with a descriptive error.
+
+- **Resource Management**:
+  - Ensures proper cleanup via `defer resp.Body.Close()` and `defer out.Close()`.
+  
+- **Progress Tracking**:
+  - Integrates [`progressbar`](https://github.com/schollz/progressbar) to display real-time download progress.
+  - Uses `DefaultBytes()` for a human-readable, byte-based indicator (e.g., "downloading 12.3 MB / 45.6 MB").
+
+- **Efficient I/O**:
+  - Leverages `io.Copy()` with an `io.MultiWriter` to stream data directly from the HTTP response body into both:
+    - The target file (`out`)
+    - The progress bar (to update on each chunk written)
+
+- **Error Handling**:
+  - Returns early with wrapped errors for network failures, HTTP non-success codes, or file I/O issues.
+
+- **Simplicity & Usability**:
+  - Minimal API surface: only two arguments (`url`, `filepath`).
+  - No external configuration needed — ideal for CLI tools or batch scripts.
+
+- **Assumptions**:
+  - No authentication, redirects, proxies, timeouts, or retries are implemented.
+  - Designed for straightforward downloads where robustness is secondary to simplicity.
+
+- **Typical Use Cases**:
+  - CLI utilities, build scripts, CI/CD pipelines.
+  - Prototyping or internal tools where advanced download features are unnecessary.
+
+- **Limitations**:
+  - Not suitable for large-scale or production-grade downloads without enhancements (e.g., retries, concurrency control).