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/whisper_local.md

@@ -0,0 +1,37 @@
+# Whisper Local
+
+- **Plugin id:** `whisper_local`
+- **Category:** Speech-to-text, local
+- **Runs:** on this machine, in-process (via `whisper.cpp`, Metal-accelerated on Apple Silicon) — no cloud, no API key
+
+## What it does
+
+Transcribes voice messages entirely on-device using [whisper.cpp](https://github.com/ggerganov/whisper.cpp). Nothing leaves the machine — the right choice when privacy matters more than raw speed, or when there's no budget for a cloud transcription API.
+
+The model (roughly 1–3 GB depending on size) is loaded into memory only when first needed ("lazy" loading) and unloaded again after a configurable idle period to free RAM — unless eager loading is turned on.
+
+## Requirements
+
+- A GGML `.bin` Whisper model file, downloaded manually onto the host filesystem — this plugin does not fetch it automatically. Example:
+  ```
+  curl -L -o models/ggml-large-v3.bin \
+    https://huggingface.co/ggerganov/whisper.cpp/resolve/main/ggml-large-v3.bin
+  ```
+  Smaller/faster models (e.g. `ggml-medium.bin`, `ggml-small.bin`) trade accuracy for speed and size — point at any of them.
+- `ffmpeg` installed on the host (used to convert incoming audio to the 16 kHz mono format Whisper needs).
+
+## Enabling & configuring (admin)
+
+1. Download a model file first (see above) and note its path.
+2. Plugin catalog → **Whisper Local** → enable, then **Configure**.
+3. Fields:
+   - **`model`** (required) — path to the `.bin` file, e.g. `models/ggml-large-v3.bin`.
+   - **`language`** — a BCP-47 code (`it`, `en`, …) or `auto` for automatic detection (default `auto`).
+   - **`load_at_startup`** — load the model into memory as soon as the plugin starts, instead of on first use (default off).
+   - **`idle_timeout_secs`** — unload the model from memory after this many seconds of inactivity, `0` = never unload (default `1200`, 20 minutes).
+
+## Notes
+
+- The model occupies roughly 1–3 GB of RAM while loaded.
+- The very first transcription after an idle unload is slower, since the model has to reload.
+- No external service and no per-use cost — the trade-off is local CPU/GPU time and disk space for the model file.