test(e2e): drop transient-5xx retry scaffolding now that the fetch storm is fixed

With the directory fetch storm eliminated (previous commit: batched
listProjects?include=documents instead of a getProject burst per modal
open), the local Supabase gateway no longer collapses under modal-open
load, so the specs' 5xx-oriented scaffolding is removed:

- create-with-retry loops (project create x2, chat create x2, workflow
  create, tabular-review create x10-attempt, review add-document x6)
- reload-guards for transient "Project not found" (waitForProjectLoaded,
  gotoProjectRow, project-assistant tab loop)
- networkidle settle-waits whose purpose was to let the per-project fetch
  burst drain before submitting (NewProjectModal / NewTRModal)
- oversized per-test timeouts justified by the storm (180s -> 60-120s)

Kept, deliberately:
- the title-generation settle logic in chat rename/delete
- chat submit's model-seeding retry loop (guards a documented
  useSelectedModel localStorage hydration race, unrelated to the gateway)
- account display-name toPass block (guards a documented profile
  hydration race, unrelated to the gateway)
- generic short networkidle settles after login/logout navigation
- Playwright's own retries: 2 on CI

Verified: with the fix, 3 consecutive full-suite runs (plus 2 more before
de-retry) were green with zero Playwright retries, running against an
account seeded with ~40 projects - a larger directory fan-out than CI's
fresh database ever produces.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>