feat: dictation round 2 — deferred transcript, adaptive meter

Owner's second live test:

- DEFERRED transcript: finals accumulate in a buffer during the run and
  flush into the primary input once, when dictation ends (Stop →
  CloseStream → Deepgram's last finals → socket close → one joined
  append; the 3s safety net covers a missing close). Nothing textual
  renders while recording — the meter is the only live feedback. Live
  output may return as a toggleable setting at the settings milestone;
  deferred is the default behavior.
- ADAPTIVE meter: cell count derives from the measured strip width (4px
  pitch, 8-48 cells, ResizeObserver; cells drop their minimum width) so
  narrow rows beside the knowledge-context slider fit — verified in the
  dev shell: draft 20 cells/83px, chat 48 cells/273px, no overlap.

docs/research/stt.md

@@ -67,3 +67,8 @@ against our codebase. Decisions at the bottom.
 - **Optimistic meter**: the click enters the meter view immediately (Stop pill + meter within one frame); the token mint and mic acquisition run concurrently (Promise.all) behind it. Esc or click-again stops.
 - **Wide idle button**: the stats-bar middle is one full-width affordance — a quiet bordered "Dictate" button when idle (error text replaces the label on failure), the Stop pill + fixed meter while live.
 - Final-appending keeps the dictate-flush separator rule (`joinDictation`).
+
+## Round-2 refinements (owner, 2026-09-17 — second live test)
+
+- **Deferred transcript**: finals buffer during the run and flush into the primary input ONCE at the end (socket-close → one joined append). Nothing textual renders while recording. Live output may return as a toggleable setting at the settings milestone; deferred is the default.
+- **Adaptive meter**: cell count derives from the meter's measured width (4px pitch, clamped 8–48, ResizeObserver; cells have no minimum width). Draft/home rows beside the knowledge-context slider show ~20 cells; chat shows the full 48. No more overflowing under neighbors.