fix(kimaki): use durable local plugin paths

[chubes4]

Summary

• Point local Kimaki/OpenCode plugin generation and repair at $KIMAKI_DATA_DIR/kimaki-config/plugins instead of the npm package directory.
• Keep the npm package plugin directory as a best-effort compatibility mirror for old local configs.
• Add a repair regression test for replacing stale local npm plugin paths with durable kimaki-config paths.

Testing

• bash tests/repair-opencode-json.sh
• bash tests/post-upgrade-restore.sh
• bash tests/path-helpers.sh
• bash tests/bridge-render.sh
• bash tests/opencode-wrapper-removal.sh
• bash tests/kimaki-session-helper-smoke.sh
• bash tests/datamachine-kimaki-adapter.sh
• bash tests/homeboy-components.sh
• bash -n upgrade.sh bridges/kimaki.sh runtimes/opencode.sh tests/repair-opencode-json.sh
• ./upgrade.sh --help

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Diagnosed the local Kimaki/OpenCode plugin path drift, drafted the shell/test changes, and ran the validation commands. Chris reviewed and directed the change.