[18.0][MIG] document_page_portal

[kwoychesko]

Migration of document_page_portal to 18.0. Part of #499.

Changes during migration (beyond the mechanical pass)

• Removed the deprecated <data> node; t-raw → t-out; Bootstrap 4 → 5 classes.
• Moved frontend assets from views/assets.xml to the manifest assets key.
• Rewrote the JS tour to an ESM module + the web_tour.tours registry API; the Python tests now use start_tour.
• Fixed the group external id knowledge.group_document_user → document_knowledge.group_document_user.
• Updated the portal My Home card to the v17+ placeholder_count pattern (it was rendering hidden).
• Replaced the removed portal.portal_record_layout with an inline card.
• Modernised the backend "edit" link from /web#… to /odoo/document.page/<id>.

A separate [IMP] commit improves the README (clearer DESCRIPTION/USAGE, fixed CREDITS link).

Tested locally on 18.0: the module installs cleanly and both portal tours pass in a headless browser.

[kwoychesko]

@marcelsavegnago — thanks in advance for reviewing 🙏

A heads-up on the red test jobs: the module installs cleanly and all 71 tests pass — both portal tours log TOUR … SUCCEEDED. The build fails on the log-error gate, which trips on a Chrome teardown warning from the two HttpCase tours:

WARNING … TestPortalDocumentPage.test_01_document_page_portal_tour: Killing chrome descendants-or-self of 328: 5 remaining
- chrome (zombie) x5

These are unreaped Chrome child processes in the CI container during HttpCase cleanup (odoo/tests/common.py), not a test failure — the tours themselves succeed. Since oca-ci fails the build on any warning (OCA/oca-ci#89), this blocks it.

Is this a known issue with browser tours in the current image (possibly Chrome-version related, cf. OCA/oca-ci#122)? Happy to adjust the tests if you'd prefer a different approach (e.g. HTTP-level checks instead of full browser tours). Thanks!