docs: rewrite generated docstrings in pipeline.py

[JodVarun]

Fixes #136

Rewrote machine-generated docstrings and inline comments in palinode/ingest/pipeline.py to natural English, matching the style established in #131 per issue #130.

[Paul-Kyle]

Close — the comments are handled exactly right, and I want to flag that first because it is the
instruction most people skim: you kept "Cap for very large PDFs" and "Simple readability: strip HTML
tags" and dropped only the generated tails, which is what the issue asked for.

Two things before I merge.

Three lines from the issue list are still untouched, all Returns: lines — current 160, 199 and
251:

• str | None: The resulting context pathway saving to memory if perfectly transcribed.
• str | None: Active reference resulting memory path.
• str | None: Successful parsed response local filepath.

And four of the rewritten lines don't match what the code does. I would rather raise these than
merge them, because the whole point of the issue is that a confident wrong docstring costs a reader
more than an obviously empty one:

• ingest_url_file Returns (:224) — "Returns target URL extracted from shortcut file." It
  returns ingest_url(...), so the value is the saved research-file path, or None. This is the one
  I would most like fixed: it is new text and it is confidently wrong.
• ingest_audio (:153) — "Stream audio chunks." It opens the file and posts it once as
  multipart; nothing is chunked.
• ingest_text (:192) — "Determine if the input string is a URL." That is the branch test, not
  the function: it ingests the text, handing off to URL ingestion when the content looks like a URL.
• write_research_file (:291) — "Generate YAML frontmatter." It writes the research file and
  returns its path; the frontmatter is a step inside that.

No rush, and none of this is a rewrite — it is seven lines. Push when you have them and I will merge
on green.

[JodVarun]

Thanks for the detailed feedback! I've updated the 3 untouched Returns: lines and corrected the 4 docstrings to accurately reflect function behavior. Pushed the update!

[Paul-Kyle]

All seven addressed — merging. Apologies for the overnight wait on the corrected push.

The one I most wanted right is ingest_url_file's return: it now says the saved research-file path
rather than the extracted URL, which is what return ingest_url(...) actually gives you. A wrong
docstring costs a reader more than a meaningless one, so that correction is the difference between
this file being fixed and being differently broken.

This is your first contribution here and it took a review round to land — that is completely normal,
and the second pass was clean. Thanks for the patience.