Stabilize mesocycle E2E test by selecting real exercise items

[Copilot]

The GitHub Actions E2E Tests job was failing in mesocycle.spec.ts because the test could click a non-exercise action row (Create New Exercise) and then assert for inputs that never render in that path. This updates selectors to target the intended UI elements only.

• Root-cause alignment

  • The failing test used broad .exercise-item and global numeric-input selectors, which are ambiguous in the current modal/editor structure.

• Selector hardening in e2e/mesocycle.spec.ts

  • Exercise selection now filters out the create-action row:
    • selects from .exercise-list .exercise-item
    • excludes entries containing Create New Exercise
  • Sets input assertion now scopes to the split-day editor’s Sets config group before resolving input[type="number"].

• Behavioral impact

  • Keeps test intent unchanged (configure sets/reps after adding an exercise) while removing false failures caused by UI action-item collisions.

const exerciseOptions = page
  .locator('.exercise-list .exercise-item')
  .filter({ hasNotText: 'Create New Exercise' });

const setsInput = page
  .locator('.split-day-editor .config-group')
  .filter({ hasText: 'Sets' })
  .locator('input[type="number"]')
  .first();