* ui: add opt-in run_javascript frontend tool
Expose a run_javascript tool to the model, executed entirely in the
browser through the existing agentic loop. Code runs in a Web Worker
inside a sandboxed iframe with an opaque origin, isolated from the
WebUI and its API. Console output, errors and the return value are
fed back as the tool result. The parent enforces a hard timeout by
removing the iframe, which terminates the worker.
Disabled by default, toggle in Settings > Developer.
* ui: address review feedback from allozaur
Use the JsonSchemaType enum for the tool definition parameter types
instead of raw string literals, extending it with STRING and NUMBER.
Move the worker shim and the iframe harness html into their own files
so the service no longer carries inline source blobs.
Replace the remaining magic strings with constants: SANDBOX_EMPTY_OUTPUT
and SANDBOX_TRUNCATION_NOTICE, and reuse NEWLINE_SEPARATOR for joins.
* ui: move sandbox worker shim to a raw imported file
Replace the inline worker template string with a real sandbox-worker.js
imported as raw text, and build the iframe harness from it in
sandbox-harness.ts. The raw worker ships as a string, not a module, so
it is excluded from eslint and the typecheck program.
