feat(agents): list every official AI SDK and Omnigent harness

[Yiminnn]

Goal

List/adapt every agent the official AI SDK and Omnigent sites publish, the same
way as the existing adapted agents. This PR focuses on listing them + documenting
each one's status — model/proxy routing correctness is the explicit next step,
not this PR.

AI SDK — now covers every official @ai-sdk/harness-*

npm's @ai-sdk/harness-* scope publishes: pi, codex, claude-code, deepagents,
opencode. The repo had the first three; this adds the last two (scaffolded from
the harness-pi template):

Package	Wraps	Status
ai-sdk-deepagents	@ai-sdk/harness-deepagents@1.0.5	🧪 scaffolded — in-process (just-bash) like Pi; routing + parity not yet verified
ai-sdk-opencode	@ai-sdk/harness-opencode@1.0.6	🧪 scaffolded — execution model (in-process vs bridge) + routing not yet verified

Both: node --check + ast.parse clean, ruff clean, test_register asserts the
name/deps/env slot, test_wire_parity skips with "no vanilla fixture yet (next step)". Added to the test-ai-sdk CI matrix.

Omnigent — one agent per orchestrated --harness

github.com/omnigent-ai/omnigent lists --harness values claude-sdk, claude-native,
codex, codex-native, cursor, cursor-native, hermes, hermes-native, opencode, pi,
pi-native, openai-agents. Registered one BenchFlow agent per distinct orchestrated
agent:

Agent	--harness	Status
omnigent-pi	pi	✅ fully worked (reward 1.0 end-to-end)
omnigent-claude	claude-sdk	🧪 listed — needs Claude Code CLI in-sandbox (next step)
omnigent-codex	codex	🧪 listed — needs the codex CLI (next step)
omnigent-cursor	cursor	🧪 listed — needs the cursor CLI (next step)
omnigent-opencode	opencode	🧪 listed — needs the opencode binary (next step)
omnigent-hermes	hermes	🧪 listed — needs the hermes CLI (next step)
omnigent-openai-agents	openai-agents	🧪 listed — needs the OpenAI Agents SDK (next step)

Mechanism: a harness param threaded through agent.py + session.py, and a
per-harness session_factory (build_omnigent_<slug>, generated as module globals so
omnigent.agent:build_omnigent_openai_agents resolves). build_omnigent_agent kept as
a pi back-compat alias. The -native run-modes are documented, not registered
(they're alternate run-modes of the same agent). register() still gates on the
session-factory seam (registers nothing on a BenchFlow without it).

"Listed-not-wired" means: the agent is in the registry, the shared install_cmd
installs omnigent itself, and the factory resolves — but each harness's own CLI
install + model routing are the next step.

Verification

• ruff clean; all server.mjs node --check; all register.py parse.
• omnigent tests: 15 passed (seam present) / 13 passed + 2 skipped (no seam).
• Status documented per agent in omnigent/README (status table + -native note),
  ai-sdk/README, and the root README (3-path table).

Not in scope (next step)

Wiring each listed harness's CLI install + verifying model routing / wire-parity. This
PR is the "list them all + document status" step the goal asked for.