docs(eln): document the v4 collection sharing model

[PiTrem]

Why

The collection-sharing refactor (#2783) and its follow-ups (#3337, #3374, #3379, #3447, #3453, #3461, #3463) shipped without any documentation update. The site still describes:

• synchronized collections as a current feature — the concept was removed outright (sync_collections_users was dropped by migration 20250827121248; no model, no API, no UI);
• a "My shared collections" tree branch, which no longer exists;
• the pre-v4 permission names (write / share / delete / import), two of them with empty descriptions;
• shared collections as not showing newly added elements — the opposite of v4 behaviour.

It also pointed at "the page Sharing", which did not exist, and linked a #synchronized-collections anchor.

This is the parallel documentation PR the ELN PR checklist asks for.

What changed

New page docs/eln/ui/collections/sharing.mdx — the permission ladder (0–5), detail levels, role shortcuts, sharing a collection or a selection, editing/revoking, groups as recipients, Shared with me, what a recipient cannot do, delegated administration, ownership transfer, export, "what sharing never does", and a v3→v4 upgrade note.

Rewritten docs/eln/ui/collections/index.mdx — the three-group tree (My Collections / Shared with me / chemotion-repo), the locked system collections, and a note on the "My projects with others" collection created by the upgrade migration. The Synchronized Collections section is gone.

Swept the sync vocabulary from faq.mdx, toolbar.mdx, inventory.mdx, first_steps.mdx, comments.mdx, system_check.mdx, ui/index.mdx and videos.mdx. The duplicated sharing chapter (and its stale role/permission table) is removed from toolbar.mdx in favour of a pointer, and Remove from all Collections is corrected — it now unlinks from your own collections only.

Release notes — adds the missing Version 4 / 4.0.0 section, which also resolves the existing inconsistency where two pages already said "available starting from version 4.0".

Scope note

This documents ComPlat/chemotion_ELN#3468 (manage and target the locked system collections) as current, per maintainer confirmation that it is robust. If #3468 changes materially before merging, the "System collections" section and management_system.png need revisiting.

Screenshots

Captured headlessly (Cypress/Electron, in-container) against a freshly seeded database, using the demo tree from #3423 — which conveniently provides one collection per permission level, a group share, a mixed group+user share, and a deliberately truncated tree.

Four v3 assets that now misrepresent the product are deleted: collection_sync.gif (a removed feature), collection_sharing.gif, sharing.png, collection_organisation.gif.

The Cypress spec that produces these images lives in the ELN repo and is proposed separately, so it is not part of this PR.

Verification

npm run build passes. The site sets onBrokenLinks, onBrokenAnchors, onBrokenMarkdownLinks and onBrokenMarkdownImages all to throw, so a clean build confirms every repointed anchor and image resolves.

The permission ladder and role presets were cross-checked against CollectionShare::PERMISSION_LEVELS, app/javascript/src/utilities/PermissionConst.js and SelectionSharingShortcuts.js.

Noted while working, not fixed here

db/schema.rb on the ELN main line cannot be loaded into a fresh database: the collection_shared_names SQL function still selects from the dropped sync_collections_users table, so db:schema:load fails and db:migrate must be used instead. Worth fixing before v4.0.0 is tagged.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XrLF2V3BSx4RLhhftvERd3