Add OpenClaw CLI provider support

[yqf-ai]

Summary

Add an openclaw CLI provider target so summarize can route summary generation through an existing OpenClaw setup instead of requiring direct provider API keys.

What this adds

• support for --model openclaw/main
• CLI_OPENCLAW environment support / detection
• OpenClaw CLI execution path in the existing CLI provider flow

Why

This lets summarize reuse an already configured OpenClaw agent/provider stack for summaries, instead of requiring separate OPENAI_API_KEY / GEMINI_API_KEY style configuration for this specific CLI.

Validation

Validated on a clean upstream base with the normal dual-package flow:

1. pack packages/core
2. pack root package
3. install both tarballs
4. run summarize with --model openclaw/main

Smoke test used:

printf 'OpenClaw summarizes through the main agent.\n' \
| node <install_dir>/node_modules/@steipete/summarize/dist/cli.js - --model openclaw/main --length short --plain

Observed successful output included:

• summarized text
• via model openclaw/main

Scope

This PR intentionally only adds the minimal OpenClaw CLI provider support.
It does not change the project's existing release model (core first, then CLI).

[yqf-ai]

Validation notes:

I verified this on a clean upstream base using the project's existing dual-package flow rather than a single-package git install path.

Steps used:

1. pnpm -C packages/core pack --pack-destination <tmp>
2. pnpm pack --pack-destination <tmp>
3. npm install --prefix <install_dir> <core_tgz> <root_tgz>
4. Run summarize with OpenClaw model target:

printf 'OpenClaw summarizes through the main agent.\n' \
| node <install_dir>/node_modules/@steipete/summarize/dist/cli.js - --model openclaw/main --length short --plain

Observed successful output included:

• summarized text
• via model openclaw/main
• elapsed timing line

This keeps the change scoped to provider support only; it does not alter the release model.

[yqf-ai]

Added a minimal CI workflow on the PR branch to cover the OpenClaw model target path: .github/workflows/openclaw-verify.yml