test(e2e): stop bounding assertions by idle-machine wall clock

[Antisophy]

Every check derivation runs one Playwright test, and nix builds them massively in parallel (max-jobs), so tests always execute on a heavily contended machine. Per-assertion timeouts were sized to idle-machine performance (the 5s Playwright default through 90s), which turns correctness assertions into de facto performance assertions: under contention the awaited condition still becomes true, but the clock fires first.

Evidence that the wait time is real and the conditions do occur (accounting per your bar for timeout changes):

• Every historically flaky check passes in 2-8 seconds when run alone; their failure durations cluster exactly at their timeout values (60s waits fail at 1.1m, 90s at 1.6m, etc.).
• The worst offenders are the multi-agent tests: e.g. project-memory performs two serial agent CLI cold starts (parent plus spawned subtask); under 32-wide contention, node cold starts alone exceed the 60s budget.
• Before this change, every full nix flake check sweep failed 2-10 of the same ~18 cells. After it: zero timeout-class failures across ~1300 test executions (two full ~600-check sweeps at full parallelism, plus four forced-rebuild rounds of the historical 18-cell flaky set running concurrently).

The change removes per-assertion wall-clock bounds as a class instead of bumping individual values: assertions and condition waits share one generous budget (9 minutes, via the expect/actionTimeout/navigationTimeout defaults and a page default timeout in the fixture), and the test timeout (10 minutes) becomes a pure hang detector rather than a performance expectation. Condition waits return the moment they are satisfied, so passing runs are exactly as fast as before; only genuine failures report slower. Explicit backend/mock readiness probes deliberately keep tight budgets, so a broken world still fails fast.

What this deliberately does not fix (and instead makes visible): running the suite surfaced genuinely intermittent defects that were previously camouflaged as fast timeout flakes and cleared by re-running. Now they fail unambiguously, burning the full budget with the condition never occurring:

• ask-answer.spec.ts:330 sometimes fails a synchronous ordering assertion (activeIndex = -1): the waiting-to-active status transition is missed by the test's event capture. No timeout is involved.
• diff-result-toggle.spec.ts:9 occasionally never renders the diff at all, even on an idle machine.
• Under sustained all-e2e contention, an agent turn occasionally wedges entirely (never completes, and teardown hangs too), suggesting a process-level failure under load.

These look like worthwhile follow-ups; this PR only removes the timeout anti-pattern so they stop hiding among false failures.

Tested with two full nix flake check sweeps plus the rebuild rounds described above; the four contention-wedge failures observed during one sweep all pass on re-run (2-5s solo).