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

[ZacharyZhang-NY]

Summary

Two more coding agents join the lazy mise-wrapper roster: Dim Agent (npm:dimcode) and Kimi Code (npm:@moonshot-ai/kimi-code). 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. New machines get the stubs from mise.sh, existing ones through a migration that respects the preinstall opt-out, and omarchy-remove-preinstalls takes both back.

Each default-agent choice launches with the spelling taken from the CLI's actual flags: bare dim opens its TUI and dim exec is the one-shot; kimi runs unattended as kimi --auto with --prompt as its one-shot. Dim has no approval prompt to skip, so it joins Pi and Ori in that comment.

The Install > AI entries are guarded by mise where rather than command presence, since the stub preinstalled on every machine would otherwise read as "installed". The menu marks at U+E90A–E90B are the Kimi simpleicon and Dim's, traced from the app icon T3-Code-style since upstream publishes no monochrome SVG.

Test plan

• test/shell.d/default-agent-test.sh covers both agents end to end: lazy stubs preserve their packages, mise.sh and the migration create them, the opt-out is respected, Remove Preinstalls deletes them, every alias canonicalizes, and both launch forms match the flags above
• test/shell.d/menu-test.sh asserts both Defaults > Agent entries with their own glyphs, the label-alphabetical order, and the font charset now spanning e900-e90b
• ./test/all: no new failures against a clean-tree baseline (git stash comparison; the dev box's pre-existing environment failures are identical before and after)
• Packages and bin names verified against the npm registry; launch flags read from each CLI's --help (dimcode 0.3.25, kimi-code 0.39.1)
• Full icon row U+E900–E90B rendered and inspected — the new marks read at menu size, existing glyphs untouched
• git diff --check clean