Persist Plutonium keys by server ID and add key management

README.md

@@ -55,6 +55,22 @@ directly.
 No token, no session, no auth freeze. If Komodo or RCON aren't configured,
 the sweep marks pending rows `manual` so nothing hangs forever.
 
+## Saved server keys
+
+Use **Server keys** to add, replace, or remove a Plutonium key for an exact
+server ID such as `t5_zombie_theater_2`. IDs use a supported map slug and a
+lobby number from 1 to 20; the server does not need to be deployed first.
+During deployment, choose the map and lobby. A saved key is reused automatically,
+and any newly entered key is saved for that ID, including if deployment fails.
+Destroying a server preserves its saved key. Updating or removing a saved key
+does not change a running server; changes apply to future deployments.
+
+Keys are stored in the application's SQLite database at `DB_PATH`, independently
+of server records. Preserve that database across container replacements. Key
+values are not returned by the management API, but are stored unencrypted in
+SQLite, so database files and backups contain credentials. Existing deployment
+keys are not automatically imported from Komodo; add them once to retain them.
+
 ## Local dev
 
 Windows or macOS — no `/root/zombies` on disk, so seed a fixture tree first.