tests: copy plugin stdio server before launch

[bolinfest]

Why

The Linux Bazel build for the permission-profile stack exposed a flaky/plugin-test-specific failure where suite::plugins::plugin_mcp_tools_are_listed resolved the test_stdio_server runfiles path successfully, but the plugin MCP subprocess later failed to spawn it with No such file or directory.

The plugin tests do not need to exercise Bazel runfiles path execution. They only need a stable stdio MCP server binary to validate that plugin-provided MCP tools are discovered and listed.

What Changed

• Copies the resolved test_stdio_server binary into the test temp home before writing the plugin .mcp.json config.
• Points plugin MCP startup at the copied executable so the child process launches from a stable local path rather than a runfiles path.
• Keeps the existing local Cargo behavior of skipping these tests when test_stdio_server is not available.

Verification

• cargo test -p codex-core plugin_mcp_tools_are_listed -- --nocapture

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Stack created with Sapling. Best reviewed with ReviewStack.

• windows-sandbox: isolate allow path computation from legacy policy #20469
• docs: avoid stale SandboxPolicy references #20468
• config tests: assert sandbox-mode fallbacks via profiles #20467
• config tests: assert permission profile runtime state #20466
• config tests: derive permission profiles directly #20465
• tui tests: assert permission profiles directly #20459
• config: gate legacy writable roots from profiles #20456
• windows-sandbox: accept permission profiles from callers #20455
• exec: localize legacy Windows sandbox projection #20452
• session: stop exposing legacy sandbox policy #20450
• protocol: remove legacy sandbox turn-context overrides #20449
• protocol: drop legacy sandbox from user turns #20446
• protocol: require permission profiles for user turns #20441
• protocol: canonicalize turn context permissions #20440
• session: localize legacy sandbox turn fallback #20438
• rollout-trace: record permission profiles #20436
• protocol: make user-turn sandbox policy optional #20433
• session: tag turns with permission profiles #20432
• core tests: submit turns with permission profiles #20431
• turn-context: stop writing legacy sandbox policy #20430
• app-server: normalize command sandbox overrides as profiles #20429
• app-server: validate turn sandbox overrides as profiles #20428
• session: convert legacy sandbox updates before settings apply #20426
• sandboxing: exercise seatbelt with runtime policies #20424
• app-server: compare resume sandbox from permission profile #20423
• mcp: send sandbox metadata as permission profile only #20422
• thread-store: stop exposing legacy sandbox policy #20421
• tui: centralize legacy sandbox projection #20420
• test support: derive turn sandbox from permission profiles #20414
• windows setup: derive sandbox from permission profile #20412
• exec tests: derive thread sandbox from profile #20411
• windows read grants: accept permission profiles #20410
• session tests: configure permissions with profiles #20409
• analytics tests: derive sandbox fixtures from profiles #20408
• approval tests: configure scenarios with permission profiles #20407
• tui: hydrate thread permissions from profiles #20406
• rollout tests: seed turn contexts from permission profiles #20404
• state: extract rollout permissions from profiles #20403
• state: derive metadata sandbox from permission profiles #20401
• otel: report conversation permissions from profiles #20400
• protocol: drop cwd-less legacy profile constructor #20398
• app-server-test-client: select permission profiles by name #20397
• session tests: configure runtime permissions directly #20396
• tests: mutate spawn-agent permission profile directly #20394
• app-server tests: select turn permission profiles by name #20393
• file-system: drop unused legacy sandbox constructor #20390
• tests: use disabled profile in exec capture check #20389
• tests: use profile constructors in config checks #20388
• tests: use permission profiles in multi-agent config checks #20387
• tests: remove sandbox policy fixture from rollout trace #20386
• tests: use permission profiles in session network checks #20384
• tests: use permission profiles in config loader checks #20382
• tests: submit websocket turns with permission profiles #20381
• tests: use permission profiles in exec policy checks #20380
• tests: use permission profiles in request permission suite #20378
• tests: use permission profiles in unified exec suite #20376
• core: use permission profiles in small read-only contexts #20375
• exec tests: launch sandbox cases from permission profiles #20372
• tests: use permission profiles in suite turn submits #20370
• guardian: configure review session permissions directly #20369
• tests: use permission profiles in small core fixtures #20368
• exec-server: use permission profiles in file system handler tests #20367
• memories: configure consolidation permissions directly #20365
• analytics: distinguish custom managed permission profiles #20363
• tests: use permission profiles in guardian config checks #20362
• tests: use permission profiles in unix escalation checks #20360
• tests: use permission profiles in patch safety checks #20359
• tests: use permission profiles in tool sandbox tests #20358
• tests: use permission profile fixtures in config checks #20357
• core: build permission instructions from profiles only #20356
• utils: summarize permission profiles directly #20355
• -> tests: copy plugin stdio server before launch #20373