docs: document make-run, fix paths stale since 0.2.0, and gate both

[hunterdsp]

make-run shipped in 0.4.0 as the headline feature and was documented
nowhere — no page, no nav entry, no line in the README. The tool whose
entire purpose is ending hand-transcribed commands could only be found by
reading its source.

What's here

A page for make-run (docs/libraries/make-run.md, Libraries nav)
covering mk-var, mk-vars, mk-run, mk-has, mk-origin, the
undefined-is-not-empty rule, and why the queries use a sentinel makefile
instead of --eval (3.82+, and macOS ships 3.81).

Source paths, wrong since 0.2.0. Scripts moved to src/just_bashit/
for Python packaging; the docs kept saying src/. Every
. just-bashit/src/datetime.sh in the README, the getting-started guide,
and all ten library pages failed for anyone who copied one — including out
of an unpacked release tarball, which carries the current layout.

README described a package layout that no longer existed, and never
mentioned uv tool install, the jb / jbx / jb-inspect entry points,
or make-run. It is the PyPI long description, so it is also the project's
front page there.

A gate, so this cannot recur. make docs-coverage asserts two things:

1. every file shipped in src/just_bashit/ is named somewhere in the docs;
2. every page under docs/ is reachable from zensical.toml's nav — an
   unlinked page builds cleanly and looks exactly like one never written.

docs/changelog.md is excluded as a mention source: it records every script
ever added, so counting it would pass everything the moment it was released.

It dispatches from pre-commit rather than DOCS_CHECK_PRE_CMDS, because CI
runs make test, make coverage and make lint — not make docs-check —
and a gate CI never reaches is a local-only gate. always_run rather than
types: [markdown], because what breaks it is adding a script, and that
commit touches no markdown at all.

A lockfile relock, in its own commit. Every uv run rewrote uv.lock
in place — the committed file predates the marker normalisation this uv
writes — so mdformat mutated a file mid-hook and pre-commit rolled back every
commit. Resolved versions are unchanged; only marker spelling.

Verification

• Both gate failure modes verified red before the fixes (page removed → fails;
  nav entry removed → fails), green after.
• make lint clean, including the new docs-coverage hook.
• make docs-check (strict build) clean: "No issues found".

🤖 Generated with Claude Code