Replace Kimaki skill directory pruning with 0.13 skill permissions

[chubes4]

Problem

Kimaki 0.13.0 ships native --enable-skill / --disable-skill flags that apply OpenCode permission.skill rules. wp-coding-agents still removes bundled skill directories via bridges/kimaki/post-upgrade.sh and bridges/kimaki/skills-kill-list.txt.

That directory-pruning workaround is brittle across npm upgrades and now duplicates upstream behavior.

Scope

• Update rendered Kimaki systemd and launchd startup commands to use explicit skill filtering.
• Preserve wp-coding-agents custom skills (upgrade-wp-coding-agents, wp-coding-agents-setup).
• Remove or retire the kill-list deletion pass and related docs/tests.
• Keep any restore path still needed for wp-coding-agents custom skills if Kimaki still only loads bundled skills paths.

Acceptance criteria

• Kimaki starts with native 0.13 skill filtering instead of deleting bundled skill directories.
• bridges/kimaki/post-upgrade.sh no longer removes arbitrary Kimaki skill directories.
• Tests cover generated service/plist args and post-upgrade behavior.
• README/changelog describe the 0.13-native behavior.

AI assistance

This issue was identified during an OpenCode GPT-5.5 review of wp-coding-agents against Kimaki 0.13.0.