fix(kimaki): use native skill filters

[chubes4]

Summary

• replace Kimaki bundled-skill deletion with native --disable-skill startup filters
• keep post-upgrade focused on restoring wp-coding-agents skills and validating persistent plugins
• update Kimaki service snapshots, docs, and post-upgrade regression coverage

Closes #146.

Verification

• tests/post-upgrade-restore.sh
• tests/bridge-render.sh
• tests/path-helpers.sh
• for f in **/*.sh(.); do bash -n "$f" || exit 1; done
• tests/datamachine-kimaki-adapter.sh
• tests/opencode-wrapper-removal.sh
• tests/kimaki-session-helper-smoke.sh
• bash tests/repair-opencode-json.sh
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Drafted the shell/docs/test changes and ran local 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Superseded by integration PR #162, which combines the Kimaki 0.13 cleanup work and resolves the overlapping bridge/test conflicts.