[SC-17216] Document cancelling PDF template outline generation from My Inbox

[emmavdh]

Pull Request Description

What and why?

Documents sc-17216 — cancelling and recovering from stalled PDF template uploads (tracker: sc-17996 / Docs 26.09). Shipped in validmind/backend#3415 and validmind/frontend#2767, both merged and live.

This resolves the open question from the earlier attempt (documentation#1469, closed): the feature's home now exists in the docs. The Start Outline From PDF flow in _create-document-templates.qmd already tells users to track progress in My Inbox — which is exactly where the new cancel action lives — so this is an incremental edit to that flow rather than a new page.

Summary of changes

One include edited, both format variants:

• New step after "Track progress in My Inbox": cancel outline generation that is still in progress — including an upload that appears stuck — via Cancel on the job in My Inbox.
• New callout on the recovery semantics, verified against the implementation:
  • Cancelling removes the uploaded PDF and leaves the template outline unchanged (backend cleans up the staged file; a cancelled job never auto-applies an outline).
  • Cancellation works even when the upload hasn't started processing — the cancel marker is durable, so a job stuck waiting for workers is dropped as soon as it is picked up (the core fix in backend#3415).
  • Cancelled jobs show as cancelled rather than failed in My Inbox (cancelled is a distinct terminal state).
• The condensed revealjs variant of the include gets a matching one-line mention.

How to test

You can just read it here - added D in below screenshot + callout box

Try the live preview (allow time for the PR preview deploy to finish):

• Manage document templates — Start Outline From PDF tab, new step d and callout

The only consumer of the edited include is manage-document-templates.qmd; it renders clean locally with quarto render --profile development (only the pre-existing validmind/validmind.qmd warning), and the new step and callout were verified in the rendered HTML.

What needs special review?

• UI labels verified against the merged frontend source (TemplatePdfParseInboxItem): the button is Cancel (no confirmation step; shows "Cancelling" while in flight), and the terminal states read "Outline generation cancelled" vs "PDF parse failed".
• Deliberately scoped to the My Inbox path. Follow-up sc-17763 adds a second cancel affordance on the template detail page, but it is unstarted (Sprint 109 / 26.10 epic) — documenting it now would describe UI that doesn't exist. It can be its own incremental edit when it ships.

Dependencies, breaking changes, and deployment notes

• Implements docs for: validmind/backend#3415 (merged), validmind/frontend#2767 (merged). No feature flag — the capability is live.
• No dependency on any other docs PR.

Release notes

You can now cancel a PDF template outline generation that is still in progress — including an upload that appears stuck — from My Inbox. Cancelling removes the uploaded PDF and leaves the template outline unchanged, so it's safe to try again. Learn more ...

Checklist

• What and why
• Screenshots or videos (Frontend) — n/a
• How to test
• What needs special review
• Dependencies, breaking changes, and deployment notes
• Labels applied
• PR linked to Shortcut
• Unit tests added (Backend) — n/a
• Tested locally
• Documentation updated (if required)
• Environment variable additions/changes documented (if required) — n/a

[github-actions]

Validate docs site

✓ INFO: A live preview of the docs site is available — Open the preview

[panchicore]

LGTM