Remove Kimaki agent normalization shim

[chubes4]

Summary

• remove the datamachine-kimaki send-argument adapter and stop installing the wp-coding-agents-owned kimaki command shim
• register native kimaki for CLI-channel dispatch and clean up legacy adapter files when their marker proves wp-coding-agents installed them
• stop stripping generic Kimaki --agent <current_agent> guidance from dm-context-filter, relying on Kimaki 0.13 unavailable-agent fallback instead
• update docs, effective-prompt snapshots, and CI coverage for the native fallback path

Closes #145.
Closes #144.

Kimaki 0.13 fallback verification

Verified against Kimaki v0.13.0 source fetched with opensrc path remorses/kimaki@v0.13.0: cli/src/session-handler/agent-utils.ts validates requested agents against OpenCode and returns agentPreference: undefined when the requested agent is unavailable, which falls back to the default/build agent instead of throwing.

Tests

• ./tests/kimaki-agent-fallback.sh
• node tests/effective-prompt/run.mjs
• ./tests/bridge-render.sh
• ./tests/opencode-wrapper-removal.sh
• ./tests/kimaki-session-helper-smoke.sh
• bash -n over all *.sh files
• git diff --check

Notes

• Local kimaki --version is still 0.12.0 on this machine, so runtime fallback verification used the fetched v0.13.0 source plus the new focused regression fixture rather than the globally installed CLI.
• homeboy test --path . --extension wordpress was also attempted; the WordPress runner reported no PHPUnit files and produced a Playground recipe crash/skip before any PHPUnit assertions could run.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Implemented the adapter removal, prompt-filter/test/doc updates, verification commands, and PR drafting for Chris to review.

[chubes4]

Superseded by integration PR #162, which combines the Kimaki 0.13 cleanup work and resolves the overlapping bridge/test conflicts.