Document today's restructures, and give data/ a README that ships with it

Plugin/unraid/README-unraid.md

@@ -105,11 +105,39 @@ once, and the endpoint, the cache writer, and the page all pick it up together.
 | `api/` | 50 | JSON endpoints the pages poll, plus action endpoints (run a script, stop a job, toggle a flag) |
 | `include/` | 16 | Shared builders and helpers — `vv_monitor_*`, `vv_arrs_*`, `vv_docker_*`, config read/write, auth |
 
-**Caching.** Several endpoints serve from `/tmp/vv_cache` (tmpfs) rather than hitting live
+**Caching.** Several endpoints serve from `$VV_CACHE_DIR` (`/tmp/varaverk/api`, tmpfs) rather than hitting live
 APIs on every page view, refreshed by `Tools/api_cache_writer.sh`. `?live=1` bypasses the
 cache. A missing or unparseable cache always falls back to a live call, so the cache can never
 be the reason a page fails to load.
 
+Anything expensive belongs in that one collection rather than in each consumer. `vv_ai_stats()`
+costs about a second — mostly waiting on Ollama and `nvidia-smi` — and the AI tab was paying it
+every 30 seconds per open tab; it is now written once to the `ai` cache and read by the tab, the
+Monitor row and the dock alike. Polling faster cannot make a figure newer, it only decides how
+soon a page notices the writer's update.
+
+> `Tools/api_cache_writer.php` rebuilds the monitor payload **independently** of
+> `api/monitor.php`, and is what the page normally reads — the endpoint only assembles one on a
+> cache miss. A key added to the endpoint and not to the writer leaves its card loading forever
+> on every ordinary page load and working only on the request that happens to miss.
+
+**One widget, rendered twice.** `include/ai_chat.php` owns the conversation surface — profile
+bar, transcript, composer, source viewer, stored-chat list — and both the AI tab and the Monitor
+tab's AI row construct it. Every id is composed from a prefix so instances can coexist, and each
+tears down the previous holder of its prefix, because Unraid swaps tab content by AJAX without
+unloading the old page's JavaScript.
+
+The Scheduler tab's dock is deliberately *not* built on it: a one-line bar that follows the view
+you have open, with its own scope chip, fix flow and incident capture, is a different component
+that happens to share an endpoint. Folding it in would produce one widget with two personalities
+and a mode flag choosing between them.
+
+**Timezone.** `include/config.php` adopts Unraid's own `timeZone` from `ident.cfg` for the whole
+PHP layer. PHP here has no `date.timezone` and therefore ran in UTC while the server ran local,
+so every date this layer produced was offset from every date the shell layer wrote — and the two
+are compared constantly. `/etc/php.ini` is the wrong fix twice over: `/etc` is a RAM filesystem
+so the edit dies at reboot, and it would retimezone every other PHP application on the box.
+
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 ## ━━━ WHAT GUARDS THE API LAYER ━━━