chore: catch doubled words in pre-commit

[thodson-usgs]

Why

A mechanical rename on another branch this week left "a label label" in a
docstring — \bsource\b matched inside the phrase "a source label" and
rewrote only the first word.

Everything green-lit it. Tests passed, mypy --strict passed, ruff passed, and
an AST comparison proving the change was behaviour-neutral passed — because
that check strips docstrings before comparing. It is silent by construction
about exactly the text a rename most easily breaks. Only reading the diff by eye
found it.

A doubled word is the mechanical signature of that mistake, and it costs
nothing to check.

Measured before adding

A gate that mostly cries wolf is worse than none, so:

	result
tracked text files scanned	168
false positives	0
real defects found on first run	1

Restricting the word to [A-Za-z]+ is what buys the zero. \w+ also matches
RDB column types such as 10n 10n in the fixture captures.

What its first run found

A typo in a user-facing demo notebook, shipped and read past:

"Filters on the the associated monitoring location's point location"

The only other hit was a genuinely clumsy test docstring — "Which variable that
is is platform-specific" — which is correct English but poor prose. Reworded
rather than excluded, so the hook needs no exclusion list beyond
tests/data/, which the existing prose hooks already skip because it holds
byte-exact API captures.

Line-scoped on purpose

--multiline was tried and rejected. It catches a doubled word split across a
wrapped line, but this repo's prose and code produce that shape legitimately all
the time — a Markdown heading followed by its own first word, return df above
df, import sys above sys:

prose (.md/.rst):  4 cross-line reports, 0 real
code  (.py):      15 cross-line reports, 0 real

19 reports, none of them defects. Line-scoped catches the shape a mechanical
rename actually produces, which is the one that got past every other gate.

It can fail

A gate never seen to fail is not evidence of anything. Seeding a doubled word
makes it exit 1 and name the location:

doubled word.............................................................Failed
- hook id: doubled-word
- exit code: 1
dataretrieval/nwis.py:1267:# seeded the the slip

The hook was run against that seed before being kept.

Scope

.pre-commit-config.yaml, one notebook typo, one reworded docstring.
Independent of #400, #402 and #403. 1139 tests pass; every hook green.

🤖 Generated with Claude Code

https://claude.ai/code/session_01JAEQqs7XzQHGQQi2KakuXD