fix(e2e): realign selectors with the olp UI and upstream route shape

upstream-main (olp's tip) ships the #215/#216 liquid-surfaces UI, so the same
selector drifts fixed on the fork's suite (commit 3d46814 on main) also apply
here. Ports those realigned hunks, plus one upstream-specific route fix.

  * Chat input placeholder is "How can I help?", not
    "Ask a question about your documents..." (ChatInput/TRChatInput). Updated in
    chat-management (rename/delete/project-assistant) and critical-path.
  * The project-assistant empty state replaced the "+ Create New" text link with
    a PillButton reading "Create" (ProjectAssistantTable) - critical-path and
    chat-management now use getByRole("button", { name: "Create" }).
  * The sidebar chat row's active marker is APP_SURFACE_ACTIVE_CLASS
    ("bg-app-surface-active"), not "bg-gray-200/60"; the row wrapper is now h-8,
    not h-9 (SidebarChatItem). The rename/delete tests locate the row accordingly.
  * The documents-toolbar folder button is "Folder" (TabPillButton wired to the
    root createFolderAction in ProjectDocumentsView), not "Add Subfolder"; it
    still opens the autofocused "Folder name" root input.
  * NewTRModal's footer submit and the tabular page CTA both read "Create", so
    the create-review helper scopes to the modal submit
    (button[name="modalAction"][value="create-review"]).
  * The built-in workflow detail test navigated to the flat /workflows/[id],
    which upstream does not route - only the typed /workflows/assistant/[id] and
    /workflows/tabular-review/[id] exist. builtin-cp-checklist is assistant-type,
    so it now navigates to /workflows/assistant/builtin-cp-checklist (the path
    the app itself links to via workflowDetailPath; works on the fork too).

Verified: full 27-test suite green against upstream-main + test-harness +
demo-mode(+provider-registry), backend + local Supabase (upstream schema.sql +
backend/migrations) + MinIO, demo model, e2e@mike.local.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CEguyEgXa9JjCciXCcVemC