fix(kimaki): use native skill filtering

[chubes4]

Summary

• Render Kimaki systemd and launchd services with native --enable-skill flags for upgrade-wp-coding-agents and wp-coding-agents-setup.
• Remove the bundled-skill directory pruning pass and delete bridges/kimaki/skills-kill-list.txt.
• Keep the post-upgrade custom skill restore path so wp-coding-agents skills are rehydrated into Kimaki's package skills directory after npm upgrades.
• Update renderer snapshots, post-upgrade smoke coverage, README, upgrade comments, and changelog notes.

Fixes #139.

Verification

• tests/bridge-render.sh
• tests/post-upgrade-restore.sh
• tests/datamachine-kimaki-adapter.sh
• bash -n across all *.sh
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Drafting the implementation, updating tests/docs, and running focused verification. Chris remains responsible for review and merge.

[chubes4]

Superseded by integration PR #162, which combines the Kimaki 0.13 cleanup work and resolves the overlapping bridge/test conflicts.