Notebook and Quarto deploys with -r uv.lock fail for a bare filename (cwd is empty) #922

Problem

Deploying a notebook or Quarto document by bare filename with -r uv.lock fails before bundling:

Inspecting Python environment...                 [ERROR]
Error: Error creating environment: Error during uv export: [Errno 2] No such file or directory: ''

Reproduce (main @ 01878e8)

From a uv project directory that contains uv.lock:

rsconnect write-manifest notebook -r uv.lock nb.ipynb    # fails
rsconnect write-manifest quarto  -r uv.lock doc.qmd     # fails
rsconnect write-manifest quarto  -r uv.lock ./doc.qmd   # works

deploy notebook and deploy quarto fail the same way.

Cause

base_dir = dirname(file) is "" for a bare filename (main.py#L2195, main.py#L3084). uv_export then builds lock_path = os.path.join("", "uv.lock") == "uv.lock" and runs subprocess.run(..., cwd=os.path.dirname(lock_path)), which means cwd="" (inspect_environment.py#L237-L262). subprocess can't chdir("").

Requirements files in requirements.txt format don't hit this because they don't spawn a subprocess with that cwd.

Expected

A bare filename works the same as ./filename. Possible fixes: resolve lock_path with os.path.abspath in uv_export, and/or normalize base_dir to "."/an absolute path when dirname() returns "".