fix(e2e): unblock full-suite CI on calendar + tags specs

[h4yfans]

Summary

The branch's CI workflow change (d1369927) flipped main from PR-only-changed-tests to running the full e2e suite. That surfaced 8 pre-existing failures in calendar.e2e.ts, calendar-comprehensive.e2e.ts, and tags-rename-delete.e2e.ts — none of which were caused by this branch, but all of which now block CI.

This PR fixes those failures so the new CI strategy can ship.

Calendar — test labels drifted from M7 redesign (commit f48b89cb)

The M7 popover redesign renamed dialog text and removed an aria-label, but the older e2e specs were never migrated:

Tests still expected	Source actually renders
heading "New Event"	heading "Create calendar event"
heading "Edit Event"	heading "Edit calendar event"
button "Create Event"	button "Create"
button "Save Changes"	button "Save"
getByLabel('Title')	input has only placeholder="New Event"

Fix: switched to the existing data-testid pattern (event-edit-popover, event-edit-save) that calendar-promote-external.e2e.ts was already using. Centralized popover() and titleInput() helpers in CalendarPO so the next label change is a one-line fix.

Calendar — Day-view chip occlusion in the rename test

Seeded Imported customer call (9:30 AM external) overlapped the test's freshly-created Memry event (9:00 AM). Even { force: true } routes the OS-level mouse click to whatever's on top — dispatchEvent('click') synthesizes the event directly on the target node and bypasses pointer routing.

Tags — duplicate aria-label="Go back"

Two buttons collided in strict mode:

• Drilldown back button: tag-detail-view.tsx:164
• Window titlebar history nav: window-controls.tsx:54 (permanently disabled)

Fix: filtered locator with :not([disabled]) since the titlebar one is always disabled by design. Real fix is to dedupe the source aria-labels — flagged as a follow-up.

Scope

Test-only changes. Zero source files touched. All 15 specs in the affected files pass locally in 48s.

Test plan

• pnpm exec playwright test tests/e2e/tags-rename-delete.e2e.ts tests/e2e/calendar.e2e.ts tests/e2e/calendar-comprehensive.e2e.ts — all 15 pass locally
• Typecheck clean for touched files (tsc --noEmit -p tsconfig.web.json)
• CI green on this PR
• CI green on the main-branch full-suite run after merge

Follow-ups (not in this PR)

• Dedupe aria-label="Go back" across window-controls.tsx, tag-detail-view.tsx, journal/date-breadcrumb.tsx — they're semantically distinct concepts but share the same screen-reader label. Once renamed, revert the :not([disabled]) filter here.
• Decide whether overlapping calendar events in Day view should render side-by-side (Google Calendar style) so users can actually click both — current layout makes the bottom event unclickable.