TST-02: Cross-browser and mobile-responsive E2E matrix expansion

[Chris0Jeky]

Source:

• docs/WIP/FutureExpansionAndImprovementsChecklist.pdf (2.9 Cross-Browser & Mobile Testing)

Horizon:

• Future expansion tranche (post current Phase 4 backlog)

Depends on:

• TST-01: Load and concurrency regression harness (k6 + multi-session Playwright) #70

Scope:

• Expand Playwright coverage beyond current smoke paths to Chromium + Firefox + WebKit profiles.
• Add mobile viewport scenario set for critical workflows.
• Define stable tagging strategy to keep CI runtime manageable.

Acceptance Criteria:

• Cross-browser suite runs deterministically for selected critical journeys.
• Mobile viewport regressions are caught for board, card edit, and navigation flows.
• Flaky cases are tracked with clear quarantine/remediation policy.
• CI docs define when full matrix runs vs smoke-only runs.

Suggested branch:

• test/e2e-cross-browser-mobile-matrix