test(e2e): execute gap plan — 57 new specs across 12 areas + cloud scaffold

[MrCoder]

Summary

Executes e2e/E2E_GAP_TEST_PLAN.md (the gap plan): 57 new passing e2e tests across 12 previously-uncovered app-level areas, authored + adversarially verified via multi-agent orchestration, plus a test.fixme scaffold for the infra-gated cases.

New specs: preview, library-actions, multipage, settings, templates, export, modals-gap, css-editor, header, mobile, telemetry, connectivity, and cloud.fixme (+ EMULATOR_SETUP.md).

Validation

• Full new suite together (local dev): 57 passed / 46 skipped / 0 failed (no cross-spec interference).
• Against staging.zenuml.com: 43 passed / 25 skipped / 0 failed (local-only tests self-skip via PW_BASE_URL).
• Adversarial verify caught + fixed: a false-green (PRV-6, see below), a flake (LIB-4 Radix race), and 3 missing staging-gate skips (MOD-1/7a/7b).

Honest fixmes (product gaps the tests surfaced — not dodges)

• PRV-6: settings.autoPreview is never wired to PreviewFrame → the auto-preview toggle is a dead control. Test documents the bug; flip to test once wired.
• EXP-1/2: no PNG/SVG export UI exists (getPng() handle has zero callers).
• SET-4: indent-size setting not connected to CodeMirror's indentUnit.
• HDR-2: title input has no Escape-to-revert.
• Auth/cloud-gated: HDR-3/4/6, CSS-5/6, SET-7, and the 35 cloud.fixme stubs (unlock via EMULATOR_SETUP.md).

Scope

• e2e/ only — no product code, no shared helpers, no existing specs modified.