#11846: media: suppress CUDA probe errors for whisper CLI

## Summary On systems without a compatible GPU (e.g. WSL2 without GPU passthrough), the auto-detected `whisper` CLI entry floods the logs with dozens of CUDA/GPU probe error lines before falling back to CPU — which works fine, just noisily. This PR: 1. **Adds `env` option to `runExec`** (`src/process/exec.ts`) so callers can pass extra environment variables to child processes 2. **Adds `env` field to `MediaUnderstandingModelConfig`** (`src/config/types.tools.ts`) so CLI media entries can declare env vars in config 3. **Sets `CUDA_VISIBLE_DEVICES=""`** on the auto-detected whisper entry (`src/media-understanding/runner.ts`) to suppress GPU probing 4. **Wires it through `runCliEntry`** — merges `entry.env` into `process.env` when spawning the CLI process ### Before ``` CUDA error: no CUDA-capable device is detected CUDA error: no CUDA-capable device is detected ... (30+ lines of GPU errors) [whisper] falling back to CPU [actual transcription output] ``` ### After ``` [actual transcription output] ``` ## Files Changed - `src/process/exec.ts` — add optional `env` to `runExec` opts - `src/config/types.tools.ts` — add `env?: Record<string, string>` to `MediaUnderstandingModelConfig` - `src/media-understanding/runner.ts` — set `CUDA_VISIBLE_DEVICES=""` on whisper entry + pass `entry.env` in `runCliEntry` ## Notes - Users can also use the `env` field in their config to set custom env vars for any CLI media entry - The `env` is spread on top of `process.env`, so existing vars are preserved unless explicitly overridden <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR adds an `env` passthrough for CLI-based media understanding entries and uses it to set `CUDA_VISIBLE_DEVICES=""` for the auto-detected `whisper` CLI entry, reducing noisy CUDA probe logs on systems without a usable GPU. It wires the new `MediaUnderstandingModelConfig.env` through `runCliEntry` into `runExec` so child processes can receive extra environment variables. <h3>Confidence Score: 3/5</h3> - Mostly safe, but env handling in runExec can break CLI execution when callers pass partial envs. - The change is small and scoped, but `runExec` forwards `env` directly without merging with `process.env`, which will drop PATH and other required variables if any caller uses the new option with a partial env object. That would cause runtime failures in affected CLI calls. - src/process/exec.ts <!-- greptile_other_comments_section --> _{(4/5) You can add custom instructions or style guidelines for the agent [here](https://app.greptile.com/review/github)!} <!-- /greptile_comment -->