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

README.md

@@ -618,10 +618,29 @@ varaverk/
 ├── Kernel/                  ← Kernel module config — loaded at boot by go file
 │   README: README-Kernel.md
 │
-└── Tools/                   ← Situational utilities: repair, export, emergency tools
-    README: README-Tools.md
+├── Tools/                   ← Situational utilities: repair, export, emergency tools
+│   README: README-Tools.md
+│
+└── data/                    ← Everything persisted on disk — the one on-disk root
+    README: data/README.md      gitignored except that README; per-host, never synced
+    ├── db/                  ← statistics, histories, counters, blocklists
+    ├── state/               ← runtime state: watchdogs, fallback, transcode, setup
+    ├── ai/                  ← retrieval index, memory, token ledger, bugs, saved chats
+    ├── cache/               ← persistent backups of the tmpfs caches, and only those
+    └── logs/                ← retained log output
 ```
 
+**State is data.** It used to live in a sibling `State_Files/`, with the conf-cache backup off in
+a third place and the arr backups loose in `data/`'s root — no single decision wrong, but nothing
+answered "what does Varaverk keep on disk". `STATE_DIR` still exists and still means the same
+thing; only its value moved, which is why that restructure touched none of the scripts built on
+it.
+
+**The RAM half is separate on purpose.** `VV_CACHE_ROOT` (`/tmp/varaverk/`) holds the WebGUI
+payload cache, the arr caches, the partner conf cache, partner token ledgers, and in-flight job
+files. It is read every second and rewritten by the hundred megabytes; it does not belong on
+flash. Both roots are defined once in `master.conf` and read by the shell and PHP layers alike.
+
 ---
 
 ## ━━━ CONFIGURATION — Configurations/ FOLDER, THREE FILES ━━━━━━━━━━━━━━━━━━━