Fix wave: dropdown keyboard/focus, appearance resets, inline key editors, content-sized slider

- MenuShell: after placement, focus lands in the search when the menu has
  one, else the body (tabIndex -1) — the lists' mount-time focus ran during
  the hidden measuring pass and silently failed, so no dropdown ever opened
  focused. The body owns the arrow machine for searchless menus:
  ArrowDown/Up cycle options with wrap (first/last entry from the body,
  native-select convention), Home/End, Enter activates, preventDefault so
  arrows never scroll the page.
- Appearance: the CSS-var applier only ever setProperty'd — a later write
  omitting a var left the stale inline value forever (empty background
  never reset, serif toggle-back looked dead). appliedNamesRef tracks what
  was set; staleVarNames (pure, exported) returns what to removeProperty.
- CommitInput: controlled — after a commit the field snaps to the stored
  record, so the clamp on a -5 prose size is visible (12), Esc reverts.
- Keys: Add-provider dropdown closes on pick; the paste row is inline
  (label | input | Save | Cancel); existing-row editors go inline with an
  explicit Cancel beside Save/Delete — folding is visible, not Esc-only.
- Graph context: readout is content-sized (tabular-nums) — no fixed-width
  dead gap when "off"; the dictation strip fills whatever space remains.

Gates: tsc clean, 866/866 tests (new staleVarNames suite), lint 0, build ok.
Live-verified via Playwright: dropdown focus+arrow cycles+wrap+Enter pick,
background set→empty reset, serif round-trip, visible clamp to 12, provider
pick closes menu, inline editor + Cancel + Esc fold, slider width 270→277px.

components/graph-context-control.tsx

@@ -60,8 +60,12 @@ export function GraphContextControl({
 				className="h-1 w-24 shrink-0 accent-primary"
 				data-testid="graph-context-slider"
 			/>
+			{/* Content-sized (owner, fix wave): the control hugs its value —
+			    no fixed-width readout means no dead gap when "off", and the
+			    dictation strip in the stats bar's middle always fills whatever
+			    space the slider leaves. tabular-nums keeps the digits steady. */}
 			<span
-				className="w-16 shrink-0 tabular-nums"
+				className="shrink-0 tabular-nums"
 				data-testid="graph-context-value"
 			>
 				{value === 0 ? "off" : `${value} tok`}