fix(web-ui): pixel loading language, tool-row sweep, composer polish

- StateDot ongoing: gradient spin ring replaced by an 8-cell pixel chase
  (2px matrix cells, stepped trail, no tweening)
- Chat: streaming pulse block replaced by a turn-level 4-pixel chase at the
  flow tail — rides the whole running turn (first-token wait, tools,
  streaming) instead of flickering with partial presence
- Tool rows (ToolRow/BashRow): running no longer swaps the icon for a dot;
  an animated mask band sweeps the row content, gliding off on exit via
  mask-position transition
- Composer: send/stop unified on the blue fill (bigger stop glyph, static
  white arrow), textarea box-sizing overflow fix, settling phase hides the
  composer while replay decides hero vs docked, workspace-placeholder
  fallback disables the bar
- Hero: glow moved behind (z-index) with lower opacity; tool-row hover icon
  crossfade at 100ms

packages/client/ui-primitives/tests/state-dot.spec.tsx

@@ -14,16 +14,17 @@ describe('StateDot', () => {
     expect(dot.getAttribute('aria-hidden')).toBe('true')
   })
 
-  it('solid states are spans; ongoing is an svg gradient ring', () => {
+  it('solid states are spans; ongoing is an svg pixel matrix', () => {
     const { container, rerender } = render(<StateDot state="done" />)
     expect(container.firstElementChild?.tagName).toBe('SPAN')
     rerender(<StateDot state="ongoing" />)
-    const ring = container.firstElementChild as SVGSVGElement
-    expect(ring.tagName).toBe('svg')
-    const circle = ring.querySelector('circle')
-    expect(circle?.getAttribute('stroke-width')).toBe('1')
-    expect(circle?.getAttribute('stroke')).toMatch(/^url\(#/)
-    expect(ring.querySelector('linearGradient')).not.toBeNull()
+    const matrix = container.firstElementChild as SVGSVGElement
+    expect(matrix.tagName).toBe('svg')
+    const cells = matrix.querySelectorAll('rect')
+    expect(cells).toHaveLength(8)
+    // Chase phase: every cell carries its own negative animation delay.
+    const delays = [...cells].map(cell => (cell).style.animationDelay)
+    expect(new Set(delays).size).toBe(8)
   })
 
   it('sizes via the size prop in both shapes', () => {