⬆️ 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/gzipfile.md

@@ -0,0 +1,37 @@
+# `obiutils` Package: File and Stream Writing Utilities
+
+The `obiutils` package provides a unified abstraction for writing data to files or streams, with optional gzip compression and buffered I/O.
+
+## Core Type: `Wfile`
+
+- Encapsulates a write-ready output stream (`io.WriteCloser`).
+- Supports both **compressed** (gzip) and uncompressed modes.
+- Uses `bufio.Writer` for efficient buffered writes.
+
+## Key Functions
+
+### `OpenWritingFile(name string, compressed bool, append bool) (*Wfile, error)`
+- Opens a file for writing.
+  - `compressed`: enables gzip compression via `pgzip`.
+  - `append`: if true, writes at end of file (`os.O_APPEND`).
+- Returns a ready-to-use `*Wfile`.
+
+### `CompressStream(out io.WriteCloser, compressed bool, close bool) (*Wfile, error)`
+- Wraps an arbitrary `io.WriteCloser` (e.g., HTTP response, pipe) in buffered/compressed I/O.
+  - `close`: if true, the underlying writer is closed on `.Close()`.
+
+## Methods
+
+- **`Write(p []byte)` / `WriteString(s string)`**:  
+  Buffered writes to the underlying stream (transparently compressed if enabled).
+
+- **`Close()`**:  
+  - Flushes the buffer.
+  - Closes gzip writer (if compressed).
+  - Closes underlying file/stream *only if* `close == true`.
+
+## Design Highlights
+
+- **Transparent compression**: Uses high-performance `pgzip` for parallel gzip.
+- **Resource control**: Explicit flag (`close`) prevents premature closure of shared writers (e.g., in pipelines).
+- **Efficiency**: Double buffering via `bufio.Writer` + gzip stream.