Make the checker executable, as its shebang promises

[sridharkalaibala]

develop is red. #858 merged at its first head, before this one-line fix, so scripts/check-installed-app.js is on develop as 100644 while carrying #!/usr/bin/env node.

tests/executable-scripts.test.js pins that a committed script with a shebang is also executable, and it is right to: a shebang is a promise that the file can be run directly, and a file that cannot is a promise broken in the one situation where somebody is already debugging something else.

not ok 767 - scripts with a shebang are executable too

This is git update-index --chmod=+x and nothing else. Verified locally:

✔ every committed shell script is executable
✔ scripts with a shebang are executable too

For the record on how it got in: the fix existed and was pushed as 1edec3ab, but GitHub never triggered CI for that push and kept reporting the older head, so the PR was merged on the strength of a stale page. That is the third time today a merge has taken a head older than what was pushed, which is worth knowing when merging soon after a push.

[github-actions]

Merged to develop. Anyone can test this - you do not need write access.

Try it at https://develop.posnic.io, or run it yourself:

git fetch origin develop && git checkout develop
npm install && npm --prefix api install
npm run dev   # then http://localhost:3000

When you have tested it, say what you did and what happened, and set
QA passed or QA failed. If you cannot set labels, just comment -
a maintainer will.

Reporting that something is broken is as useful as fixing it. It is
better found here than by a shopkeeper.