test(e2e): drop stale first-run needs_connection tests

[Astro-Han]

Summary

#1720 (opencode-free as a zero-credential default provider) added ensureBootstrapConnection, which unconditionally seeds an opencode-free connection on first launch when no connections exist. The E2E gate that skips it, if (!e2eFixture), only triggers when MAKA_E2E_FIXTURE is set, but the emptyWindow fixture (used by all four first-run.spec.ts tests) passes seed: false and no e2eFixtureScenario, so MAKA_E2E_FIXTURE is unset and the bootstrap runs — seeding opencode-free into the "empty" workspace. The onboarding state becomes ready_empty instead of needs_connection, so OnboardingHero no longer renders .maka-firstrun-row, and the four tests fail with toHaveCount 0 / click timeouts.

This is a deterministic regression on current main (not a flake): #1720's own e2e failed exactly these four; every post-#1720 run fails them identically; pre-#1720 runs passed. #1720 merged with the failing e2e, so every PR's e2e is now red on these four.

The needs_connection first-run hero is now unreachable for a fresh install (opencode-free is always seeded, and re-seeded whenever the connection list is empty), so these tests assert a contract that no longer holds. Drop them now to unblock e2e. Follow-up will add coverage for the post-#1720 fresh-install boot contract (opencode-free seeded -> ready_empty). The now-unused emptyWindow fixture ("Used by first-run only") is removed too.

Unblocks the plan-reminder focus-restore fix (#1723) and the docs PR #1719, whose e2e runs merge with main and so also hit this cluster.

Verification

• npx playwright test --list --config e2e/playwright.config.ts: parses the remaining 93 tests across 32 files with no import/syntax errors.
• emptyWindow has no remaining references across the repo.
• The 93 remaining tests passed in the CI runs that failed only on these four, so deleting these four leaves e2e green.

Review focus

This drops test coverage of the needs_connection first-run hero to unblock CI. The follow-up (tracked separately) should add E2E for the new fresh-install boot contract. If the team instead wants to keep exercising the needs_connection hero, the alternative is to gate ensureBootstrapConnection in E2E (e.g., skip it when isE2e/isIsolatedE2e, not only when e2eFixture) so emptyWindow boots without opencode-free — say so and I'll switch the approach.