fix(coding-agent): kernel test fixtures speak protocol 3

[snimu]

Summary

• the fake-runtime fixtures in repl-kernel-protocol-corruption.test.ts (lines 35/38) and ipython-provisioner.test.ts (line 76) hardcode protocol: 2, while repl-manager.ts requires REPL_PROTOCOL_VERSION = 3
• as a result, current main deterministically fails 23 tests across these two files in any clean environment ('Kernel runtime speaks protocol 2, expected 3')
• update the three fixture occurrences to protocol 3; repo-wide grep confirms no other stale fixtures
• REPL_PROTOCOL_VERSION is module-private, so the fixtures use the literal rather than importing it

Validation

• both suites: 39/39 pass (previously 23 failed / 16 passed in the identical environment)
• npm run check: biome, tsgo, installer render, and browser smoke all pass
• test-only change; no changelog fragment required (fragment check triggers on src/ changes only)

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Note

Low Risk
Only updates embedded test fixture strings; no runtime or security impact.

Overview
Test-only fix: fake Node-based REPL runtimes in ipython-provisioner.test.ts and repl-kernel-protocol-corruption.test.ts now advertise protocol: 3 on their ready events instead of protocol: 2.

That matches what ReplKernelManager enforces (REPL_PROTOCOL_VERSION = 3), so kernel tests stop failing immediately with “Kernel runtime speaks protocol 2, expected 3” before exercising provisioner or protocol-corruption behavior. No production code changes.

^{Reviewed by Cursor Bugbot for commit a97f699. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Bump kernel test fixtures to protocol 3

Updates the protocol field from 2 to 3 in the ready event emitted by embedded child-process scripts across two test fixtures. Affects both the normal boot path and the READY_WITH_GARBAGE path in the fake REPL script.

^{Macroscope summarized a97f699.}