fix(icons): say "background work", not "to-do list", and lighten the terminal glyph

Two glyphs read wrong in the live instance:

- Tasks shows subagent sessions AND the host's background jobs, so a checklist
  glyph described a page that does not exist. `VscLayers` (sheets stacked, i.e.
  work running behind the conversation) says what the page is; the amber token
  stays, so it still reads as live activity.
- The terminal was the widest glyph in the set and the only bare fill in a
  strip of the plugin's own 1.5px-stroked icons, which made it look like a
  heavy foreign block. It now renders a step down (0.85x the strip size, floor
  10px) and every colored tab glyph gets a hairline outline of its own ink
  (`stroke: currentColor` + `non-scaling-stroke`, so the line stays one device
  pixel across the sets' mixed 16- and 24-unit viewBoxes; `paint-order: stroke`
  centres it on the fill edge instead of fattening the shape).

tests/builtins.spec.ts pins both readings by glyph identity (tasks = layers,
terminal = the shrunk, outlined VscTerminal), so a future swap has to argue
with a failing assertion rather than with a comment.

Gates: typecheck / lint green, pnpm test 127 files / 1343 passed / 9 skipped.

tests/builtins.spec.ts

@@ -8,6 +8,8 @@
  * tab (git lens + session lens, PR #471's file-trace merged in).
  */
 import { describe, expect, it } from 'vitest'
+import type { ReactElement } from 'react'
+import { VscCommentDiscussion, VscGitCommit, VscGlobe, VscLayers, VscTerminal } from 'react-icons/vsc'
 // First import: browser globals before the xterm-carrying builtin graph loads.
 import './browser-globals.ts'
 
@@ -235,6 +237,36 @@ describe('built-in tab registrations', () => {
       expect(tab.icon, tab.id).toBeDefined()
     }
   })
+
+  it('the tab glyphs say what the page shows (colored, token-driven)', () => {
+    const { service } = setup()
+    const iconOf = (id: string): ReactElement => {
+      const icon = service.getTab(id)?.icon
+      expect(icon, id).toBeDefined()
+      return (typeof icon === 'function' ? icon(14) : icon) as ReactElement
+    }
+    // Every colored glyph is [wrapper][glyph]; unwrap the themed wrapper.
+    const glyphOf = (id: string): unknown => {
+      const wrapper = iconOf(id) as ReactElement<{ children?: ReactElement }>
+      return (wrapper.props.children as ReactElement | undefined)?.type ?? wrapper.type
+    }
+    // Tasks lists subagent sessions AND background jobs — layered sheets say
+    // "work running in the background"; a checklist glyph would say "to-do
+    // list", which this page is not.
+    expect(glyphOf('subagent')).toBe(VscLayers)
+    expect(glyphOf('git')).toBe(VscGitCommit)
+    expect(glyphOf('sidechat')).toBe(VscCommentDiscussion)
+    expect(glyphOf('browser')).toBe(VscGlobe)
+    // The terminal glyph is the widest in the set: it renders a step down from
+    // the strip's size and keeps a hairline outline so it matches the plugin's
+    // own drawn chrome instead of reading as a heavy filled block.
+    const wrapper = iconOf('terminal') as ReactElement<{ children?: ReactElement }>
+    const terminal = wrapper.props.children as ReactElement<{ size?: number; style?: Record<string, unknown> }>
+    expect(terminal.type).toBe(VscTerminal)
+    expect(terminal.props.size).toBeLessThan(14)
+    expect(terminal.props.style?.strokeWidth).toBe(1)
+    expect(terminal.props.style?.vectorEffect).toBe('non-scaling-stroke')
+  })
 })
 
 describe('built-in file viewer registrations', () => {