docs: surface 'hermes setup --portal' and 'hermes portal' across user-facing pages (#30869)

PR #30860 added a one-shot Portal setup command and a small portal CLI
surface. Update the docs so the new commands are discoverable without
upgrading the tone of existing Portal mentions.

- getting-started/quickstart.md: small tip near Choose a Provider
  pointing at 'hermes setup --portal' as the easiest fresh-install path.
- user-guide/features/tool-gateway.md: lead the Get-Started section
  with 'hermes setup --portal' for fresh installs, keep 'hermes model'
  for already-configured users, and add 'hermes portal status / tools'
  to the activity-check commands.
- user-guide/features/{web-search,image-generation,tts,browser}.md: the
  existing 'Nous Subscribers' tip blocks now name the one-shot command
  for new installs, keeping the existing 'hermes tools' path for users
  who only want to swap a single backend.
- reference/cli-commands.md: register 'hermes portal' in the top-level
  command table, add a 'hermes portal' section with subcommands, and
  add '--portal' to the 'hermes setup' options table.

Tone: each page already had a Portal mention. This PR keeps the per-page
count to one and uses concrete CLI commands rather than promotional copy.
Tool Gateway page is the one exception (the whole doc is about Portal).

website/docs/getting-started/quickstart.md

@@ -88,6 +88,16 @@ The single most important setup step. Use `hermes model` to walk through the cho
 hermes model
 ```
 
+:::tip Easiest path: Nous Portal
+One subscription covers 300+ models plus the [Tool Gateway](../user-guide/features/tool-gateway.md) (web search, image generation, TTS, cloud browser). On a fresh install:
+
+```bash
+hermes setup --portal
+```
+
+That logs you in, sets Nous as your provider, and turns on the Tool Gateway in one command.
+:::
+
 Good defaults:
 
 | Provider | What it is | How to set up |