test(ai): require explicit opt-in for Ollama live tests

[ChickenBreast-ky]

Why

A normal npm test run treated the presence of the ollama executable as permission to enter the live Ollama suite. That path can pull gpt-oss:20b, start a local server, and load a large model without explicit consent.

What changed

• Gate Ollama discovery behind PI_ENABLE_LOCAL_LLM=1 or PI_ENABLE_LIVE_API_TESTS=1.
• Keep the actual which ollama command inside the shared gate and mock that command boundary in regression tests.
• Verify the default path does not probe Ollama and both explicit opt-in paths do.
• Update test.sh to clear the opt-in flags instead of exporting the retired PI_NO_LOCAL_LLM opt-out flag.
• Record the fork-specific change and expected conflict zones in packages/ai/changes.md.

Validation

• npx vitest run packages/ai/test/live-api-gates.test.ts packages/ai/test/stream.test.ts
• npx biome check --error-on-warnings packages/ai/test/live-api-gates.ts packages/ai/test/live-api-gates.test.ts packages/ai/test/stream.test.ts
• npx tsgo --noEmit
• bash -n test.sh
• npm run build
• npm test

The default-env runs did not start an Ollama process, open TCP 11434, or modify the Ollama server log. The positive live Ollama suite was intentionally not executed; its opt-in boundary is covered with a mocked command.

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Summary by cubic

Require explicit opt-in to run Ollama live tests so npm test no longer probes or starts local models by default. The probe is now portable across Unix and Windows.

• Bug Fixes

  • Gate Ollama discovery behind PI_ENABLE_LOCAL_LLM=1 or PI_ENABLE_LIVE_API_TESTS=1 and short-circuit before probing; use which on Unix and where on Windows.
  • Replace the legacy PI_NO_LOCAL_LLM opt-out; update tests to mock child_process.execSync and update test.sh to unset the new opt-in flags.
  • Update stream.test.ts to use the shared availability check and skip by default.

• Migration

  • To run the live Ollama suite, set PI_ENABLE_LOCAL_LLM=1 or PI_ENABLE_LIVE_API_TESTS=1.

^{Written for commit 6393b5b. Summary will update on new commits.}