fix: install Mad Libs from a symlinked package path

[theycallmeswift]

The Mad Libs install hook now resolves its package directory with pwd -P. npm 11's npm ci fails with "Missing:

@ from lock file" when --prefix is a path through a symlink, which made the package "Install failed" on a demo station, whose home is under macOS's /tmp.

Decide

Nothing.

Ready gate

Step	Evidence
Tests and lint	npm run verify: ok for all three packages. npm run lint: 0 issues in 15 files. npm test on macOS: 190 of 192 pass; the two failures are BirdsBirdBirds tests, covered under Skipped tests.	✅
Red run	The install test, now run through a symlink, fails without the fix with npm error Missing: linked-package@ from lock file and passes with it.	✅
Sibling sweep	Searched hooks, docs, and tools for --prefix and npm ci: this is the only hook that passes its path to npm. setup and cleanup pass theirs to cp and node, which follow symlinks.	✅
Docs and specs	None: the hook's contract and the package's README are unchanged.	✅
Standalone run	./install from the clone succeeds, and the install test loads the extension under the pinned Pi. npm run demo in boothstrap.sh now lists the package as installed. No model playthrough, since only the install path changed.	✅
Editorial pass	Reread against docs/style/; the hook gets one why-comment.	✅
Skipped tests	None skipped. On macOS, "the server refuses a body over the cap with 413" fails with EPIPE on unmodified main too. "the watcher reports a bird.png that appears, once" passed on main in a rerun, so it is flaky. Both are outside this change; CI runs on Linux.	✅
Secrets, permissions	Not touched.	✅

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