test(web): navigation & panes scenarios over one rich seeded session

One two-turn seed (turn 1: bash + two parallel reads in a single assistant
message; turn 2: a markdown-heavy reply) rendered cold through the
seeded-history pattern — zero model calls — serving four surfaces:

- sidebar search: client-side title filter; asserted only after the durable
  title lands with the attach baseline (a cold SessionSummary carries no
  title — search matches the displayTitle the user sees). Negative query
  empties the tree, positive narrows to the match + its force-expanded
  group, clear restores.
- Trajectory tab: turn sections, the step group's tool mix ('bash read×2'),
  and a view-area aria golden.
- Waterfall tab: span stats header + one lane per span. The P-I fold counts
  a turn-0 prologue span (only assistant/steering nodes carry a turn
  number) — pinned as-is; real spans are P-III per the view's ledger.
- details column: the bash toolview row routes click to openDetails;
  open/closed is asserted on the frame's data-details-collapsed attribute
  because close collapses the grid column to width 0 without unmounting
  the subtree (hidden, not absent, is the contract).

Agent Note scenario list extended in both languages; pairing re-recorded.

apps/web/tsconfig.json

@@ -26,6 +26,7 @@
     "tests/live-interactions.e2e.ts",
     "tests/question-composer.e2e.ts",
     "tests/steering.e2e.ts",
+    "tests/navigation-panes.e2e.ts",
     "tests/replay-round-trip.e2e.ts",
     "tests/seeded-history.e2e.ts"
   ],