Increase coverage for a Meticulous project

Run meticulous-cli-update first if you haven't already this conversation (it also covers authentication and project selection).

What you deliver

Two separate outputs, both expected — neither substitutes for the other:

1. One or more test runs from newly recorded sessions that provably extend coverage. "Provably" means a comparison against the baseline naming the files whose coverage went up, and by how much (Step 7). If a target turns out not to be coverable, say so rather than padding the list.
2. A PR proposing .meticulousignore changes. Only include paths — most often whole directories — that you are confident are not coverable at all. Anything you merely failed to reach in one sitting does not belong there; leave it out and mention it in the PR description instead.

Before you start: run this on main, with a clean tree

Every command below relies on the CLI resolving things from your local checkout: js-coverage defaults to the current git HEAD, trigger-test-run defaults to HEAD for the deployment and to the merge-base with the origin default branch for the base. On main with a clean tree those collapse to a single commit, which is exactly what you want — no diff, a head-only run, and a union in Step 7 that the API will actually accept.

Off main this breaks in ways that are tedious to unpick: union coverage is rejected unless every run executed the exact same commit, and a PR's merge commit is recomputed whenever its base branch moves, so a run triggered earlier against a since-advanced base no longer unions with a new one.

So: check out main, pull, and make sure git status is clean before Step 1.