Docs: generated settings block is missing the extensions category

### What happened?

The autogenerated settings block in `docs/reference/configuration.md` is missing the entire `extensions` category, so it looks like the generated docs haven't been refreshed since that category was added.

`extensions` is defined in `packages/cli/src/config/settingsSchema.ts` (around line 2481) with two settings:

- `extensions.disabled` — "List of disabled extensions." (array, default `[]`)
- `extensions.workspacesWithMigrationNudge` — "List of workspaces for which the migration nudge has been shown." (array, default `[]`)

Both are present in `schemas/settings.schema.json`, so the schema is current. But inside the `` / `` block in `configuration.md` there is no `#### extensions` heading and no entry for either setting. The block currently documents 23 categories; `extensions` isn't one of them. It also isn't covered by the hand-written sections that follow the end marker (`mcpServers`, `telemetry`).

This doesn't look intentional. `scripts/generate-settings-doc.ts` only skips entries when `showInDialog` is false *and* `includeAll` is off — and `configuration.md` clearly runs with `includeAll`, since plenty of `showInDialog: false` settings are documented there (`general.vimMode`, `general.preferredEditor`, `ui.theme`, and others). So `extensions.*` should be emitted, and every other category in the schema is.

I checked whether anything else had drifted: comparing all 220 leaf settings in the schema against the entries in the doc, `extensions.disabled` and `extensions.workspacesWithMigrationNudge` are the only two missing. So it's just this one category.

The fix is presumably to run `npm run docs:settings` and commit the result. I didn't open a PR for it because I'd have to hand-write what the generator emits rather than run it, and I'd rather not introduce drift inside an autogenerated block — regenerating it locally is a one-command fix for someone with the repo set up.

### What did you expect to happen?

The generated settings block in `configuration.md` should list every category in `settingsSchema.ts`, including `extensions`.

### Client information

Not a runtime issue — a drift between `packages/cli/src/config/settingsSchema.ts`, `schemas/settings.schema.json` and `docs/reference/configuration.md` on current `main` (package version `0.56.0-nightly.20260806.g761f604c1`).

Reproducible with: `grep -c "extensions.disabled" docs/reference/configuration.md` returns `0`, while the same key is present in `schemas/settings.schema.json`.

Start with docs/reference/configuration.md and the generator entry point scripts/generate-settings-doc.ts; inspect how npm run docs:settings is configured to include all settings. Run npm run docs:settings, then verify the autogenerated block includes the extensions heading and both extensions.disabled and extensions.workspacesWithMigrationNudge entries, matching packages/cli/src/config/settingsSchema.ts and schemas/settings.schema.json.

Written by the indexing model from the issue text.