perf(extensions): quiet runtime success logs

[JustYannicc]

What changed

• Added an explicit extension-runtime debug flag, __SUPERCMD_EXTENSION_RUNTIME_DEBUG, for verbose extension-loader diagnostics.
• Gated module-load React logs, fakeRequire React/jsx logs, successful load logs, and ViewRenderer success logs behind that flag.
• Kept warning/error diagnostics for failed or suspicious extension loads.
• Added a focused source-level regression test for quiet success-path logging and exported-function toString avoidance.

Why

Successful extension/menu-bar/background bundle evaluation currently emits hot-path diagnostics and stringifies exported functions during normal operation. That adds console noise and avoidable work on extension loads and remounts.

Compatibility impact

No fakeRequire module resolution, wrapper semantics, timer cleanup, or Raycast shim exports changed. Verbose success diagnostics remain available by setting globalThis.__SUPERCMD_EXTENSION_RUNTIME_DEBUG = true; warnings and errors still log by default.

How tested

• node --test scripts/test-extension-wrapper-cache.mjs scripts/test-extension-sync-facade.mjs scripts/test-background-no-view-dedupe.mjs scripts/test-extension-runtime-logging.mjs on the integration stack before clean-branch extraction: 15 passing tests.
• Same command on this clean upstream-main branch runs the available logging harness: 4 passing tests. The other three neighboring harness files are not present on upstream main yet.
• mcp__lsp.diagnostics for src/renderer/src/ExtensionView.tsx: no errors.

Evidence from the logging harness:

• Before model: [baseline] extension runtime success diagnostics: logs=4 exportedToStringCalls=1
• After helper: [after] extension runtime debug helper: defaultDebugCalls=0 enabledDebugCalls=1

Stack validation

Draft while #530, #531, #532, #533, #534, and #535 are still pending. This PR branch is clean against upstream main and contains only the extension runtime logging fix.

[JustYannicc]

Superseded by consolidated runtime lifecycle/icon churn PR #558: #558