test(e2e): seed Runtime Host policy authority

[MoonOld]

Summary

• Seed Desktop Playwright connections through the current Runtime Host policy authority after refactor: remove legacy runtime policy migration #2700 removed the legacy migration.
• Persist credentials, model inventories, and the default target, then release the root owner before Electron starts.
• Assert the public Host-backed onboarding projection before exercising the real session send path.

Fixes#2705

Verification

• npm --workspace @maka/desktop run build:with-deps
• npm run lint
• npm run typecheck
• settings.spec.ts: 3 passed
• send-message.spec.ts: 1 passed
• send-message.spec.ts + settings.spec.ts, --repeat-each=3: 12 passed
• Hosted Linux CI: 17/17 Desktop E2E passed and the alignment audit was clean (run).
• Full Desktop E2E locally: 16 passed; the existing macOS Home caret assertion in slash-command-menu.spec.ts failed identically on the pre-refactor: remove legacy runtime policy migration #2700 baseline.
• npm run format:check: blocked by 62 existing files outside this diff; chore: finish test cleanup #2702 fixes that baseline.
• npx knip --workspace apps/desktop: blocked by the existing unused session-list-render-helpers.ts; chore: finish test cleanup #2702 removes it.

Root cause

The shared fixture still wrote legacy connection and credential files. With migration removed and automatic bootstrap disabled for the Desktop E2E candidate, Runtime Host saw an empty catalog and 16 tests stopped at onboarding before their assertions.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

[MoonOld]

@Astro-Han@jackwener could you review this fixture-only fix? Hosted Linux Desktop E2E is now 17/17 green. The remaining typecheck red is the 62-file formatter/Knip baseline fixed by #2702; conversely, #2702 is green there and only lacks this E2E fix. After either complementary PR lands, the other can rebase to an all-green base.

[Astro-Han]

Approved — no P0–P3 findings at c17a37d1.

This fixes the fixture at the right boundary: the test setup now seeds the authoritative Runtime Host policy stores, including credentials, model inventories, and the default target, then releases root ownership before Electron starts. The added assertion verifies the public Host-backed onboarding projection instead of only relying on the composer becoming visible.

I verified that Hosted Linux Desktop E2E passes 17/17 and that the changed files are format-clean. The remaining typecheck failure is the unrelated 62-file formatter baseline covered by #2702. Please rebase after that complementary fix lands and require an all-green head before merging.

Disclosure: Codex assisted with tracing the two-file diff, storage-authority seams, and CI evidence. Astro-Han reviewed this conclusion and owns the approval decision.

[MoonOld]

Closing as superseded by #2742, which has already landed the authoritative Runtime Host fixture seeding on main. Thanks for the review and approval.