Enhance logging and progress handling in SSH operations

- Updated the `_log_default` function to handle messages starting with `\r` for in-place updates.
- Introduced `split_ssh_stream` to differentiate between line and progress events in SSH output.
- Implemented `feed_ssh_log` to dispatch log messages based on event type.
- Refactored `_stream_pty_output` to utilize the new logging and event handling functions.
- Enhanced the `log` function in `term.py` to support progress updates, ensuring a cleaner output experience.
- Updated `DownloadProgress` classes in `civitai_fetch.py` and `llamacpp_fetch.py` to print progress in place, improving user feedback during downloads.

tests/test_ssh_stream.py

@@ -0,0 +1,33 @@
+"""SSH stream splitting for in-place progress bars."""
+
+from gpu_rent.ssh_ops import feed_ssh_log, split_ssh_stream
+
+
+def test_split_crlf_line():
+    events, rest = split_ssh_stream("hello\r\n")
+    assert events == [("line", "hello")]
+    assert rest == ""
+
+
+def test_split_progress_cr():
+    events, rest = split_ssh_stream("prog 10%\rprog 20%\r")
+    assert events == [("progress", "prog 10%"), ("progress", "prog 20%")]
+    assert rest == ""
+
+
+def test_split_mixed_progress_then_line():
+    events, rest = split_ssh_stream("a\rb\r\nok\npartial")
+    assert events == [
+        ("progress", "a"),
+        ("line", "b"),
+        ("line", "ok"),
+    ]
+    assert rest == "partial"
+
+
+def test_feed_progress_prefix():
+    seen = []
+    feed_ssh_log(seen.append, "progress", "50%")
+    assert seen == ["\r50%"]
+    feed_ssh_log(seen.append, "line", "done")
+    assert seen[-1] == "done"