docs overhaul: agent-facing doc bundle, read-only docs mount in containers

- Strip ~55 stale upstream docs (dev docs never meant for the agents)
- Write new slim index.md as an agent-facing guide to the app's features
- Add new plugin docs: comfyui, elevenlabs, kokoro_tts, orpheus_tts_3b,
  remote_connectivity, whisper_local (replacing old names)
- Add docs_host to UserFs: docs/… and ~/docs/… resolve to {WD}/docs,
  mounted read-only at /root/docs in every user's container
- Instruct assistant/kid/project-coordinator agents to read docs/index.md
  when users ask how the software works

docs/plugins/elevenlabs.md

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+# ElevenLabs
+
+- **Plugin id:** `elevenlabs`
+- **Category:** Cloud text-to-speech + transcription
+- **Runs:** calls the ElevenLabs cloud API — needs internet and an ElevenLabs account
+
+## What it does
+
+Adds [ElevenLabs](https://elevenlabs.io) as a provider of both realistic text-to-speech voices and speech-to-text transcription. Unlike the local TTS/transcription plugins, nothing runs on this machine — every request goes out to ElevenLabs' servers and is billed on their account.
+
+Enabling the plugin does not by itself add any voice or transcription model — it only makes "ElevenLabs" available as a provider type. Models are added separately in the Models hub (see below), same as any other cloud LLM/TTS/transcription provider in this app.
+
+## Requirements
+
+- An ElevenLabs account and an API key (from the ElevenLabs dashboard).
+
+## Enabling & configuring (admin)
+
+1. Plugin catalog → **ElevenLabs** → enable. (This plugin has no config form of its own.)
+2. Go to the Models hub → **LLM Providers**, add a new provider, choose type **ElevenLabs**, paste the API key (stored as a secret field, not shown again after saving).
+3. Go to the Models hub → **Transcription** and/or **TTS**, add a model, pick the ElevenLabs provider just created, and choose a voice/model from the list — fetched live from ElevenLabs, so it always reflects what's actually available on that account.
+
+## Notes
+
+- Usage is billed by ElevenLabs per character (TTS) / per minute (transcription) according to the account's plan.
+- Several ElevenLabs voice models understand inline markup for expressiveness: `<break time="0.5s" />` for pauses, `<phoneme alphabet="ipa" ph="...">word</phoneme>` for pronunciation, `(laughs)`/`(sighs)`/`(coughs)` for non-verbal sounds, and ALL CAPS or repeated letters for emphasis. Worth mentioning to a user who wants more expressive speech.
+- One provider entry can supply both a TTS model and a transcription model — they don't need to be added twice.