Add Dim and Kimi Code to the agent roster and Install > AI

Both install through the lazy mise wrappers (npm:dimcode and
npm:@moonshot-ai/kimi-code), preinstalled on new machines and migrated onto
existing ones unless preinstalls were removed, and each gets a menu entry in
both places: under Setup > Defaults > Agent as a default-agent choice, and
under Install > AI for installing without changing the default. The launch
spellings come from each CLI's actual flags — bare dim is the TUI and `dim
exec` the one-shot, kimi runs full-auto as `kimi --auto` with `--prompt` as
its one-shot. The Install > AI entries are guarded by `mise where`, since the
preinstalled stub would otherwise read as installed. The menu marks are the
Kimi simpleicon and Dim's traced from its app icon, since upstream publishes
no monochrome SVG.

test/shell.d/menu-test.sh

@@ -226,6 +226,8 @@ const expectedAgents = {
   grok: { icon: '\ue904', iconFont: 'omarchy', label: 'Grok' },
   copilot: { icon: '', label: 'Copilot' },
   crush: { icon: '󰋑', label: 'Crush' },
+  dim: { icon: '\ue90a', iconFont: 'omarchy', label: 'Dim Agent' },
+  kimi: { icon: '\ue90b', iconFont: 'omarchy', label: 'Kimi Code' },
 }
 assert(
   Object.entries(expectedAgents).every(([agent, expected]) => {
@@ -244,7 +246,7 @@ assertDeepEqual(
   defaultItems
     .filter(item => item.parent === 'setup.default.agent')
     .map(item => item.label),
-  ['Antigravity', 'Claude', 'Codex', 'Copilot', 'Crush', 'Grok', 'omp', 'OpenCode', 'Ori', 'Pi'],
+  ['Antigravity', 'Claude', 'Codex', 'Copilot', 'Crush', 'Dim Agent', 'Grok', 'Kimi Code', 'omp', 'OpenCode', 'Ori', 'Pi'],
   'menu sorts coding agents alphabetically'
 )
 const expectedDefaults = {
@@ -636,5 +638,5 @@ assert(
 JS
 
 font_charset=$(fc-query --format='%{charset}' "$ROOT/default/fonts/omarchy/omarchy.ttf")
-[[ $font_charset == *"e900-e909"* ]] || fail "Omarchy icon font includes every custom menu glyph"
+[[ $font_charset == *"e900-e90b"* ]] || fail "Omarchy icon font includes every custom menu glyph"
 pass "Omarchy icon font includes the official agent marks"