Fix raw HTML in Google Calendar event descriptions

[martin-forge]

Problem

The Google Calendar API documents the event description field as one that can contain HTML, and Calendar's own editor stores markup there. TaskNotes consumes that string as plain text everywhere: event tooltips, the ICS event info modal, "copy as markdown", the {{icsEventDescription}} template variable, generated note bodies, and folder templates.

Several of those write the value into the vault, so raw markup was not only displayed — it was persisted into note bodies and folder names.

Fix

Normalize the description once at the Google provider boundary, parsing it with Obsidian's HTML sanitizer. Paragraph breaks, list structure, and link addresses survive the flattening.

Plain text is returned unchanged, so descriptions that merely contain angle brackets — Contact <user@example.com>, placeholders such as <TBC> — are untouched. Normalizing at the boundary keeps every consumer plain-text rather than making each one handle HTML separately. ICS subscriptions read descriptions through their own path and are unaffected.

Why not a plain textContent read

textContent drops paragraph and list breaks and discards href values, so a description holding a bulleted agenda and a meeting link collapses into one run-on line with the link gone. The flattening pass exists to keep those three things and nothing more.

Descriptions sent back to Google

Writes are unaffected. TaskCalendarSyncService rebuilds the description from the task before every update, and the drag/resize path sends only start and end. The normalized value is never round-tripped into Calendar, so formatting a user has set there is not flattened by this change.

Relationship to earlier work

This complements #1882, which fixed the TaskNotes-to-Google export; this covers the Google-to-TaskNotes input side. It is also the actual cause behind #2102, which I closed after testing: the entity handling I proposed there was a symptom of descriptions being read as plain text, not the underlying problem.

Validation

npm test -- tests/unit/utils/calendarDescription.test.ts tests/services/GoogleCalendarService.test.ts
npm run typecheck
npm run lint
npm run build

50 focused tests pass. The full suite shows no new failures against current main. Rebased on current main.

[callumalpass]

Thanks for the contribution, @martin-forge!