issue 1859: modes by account, and the reading pane with its corrections; name a nameless sender (1859.4, 1850)

ADR 0515 §4, §5: the trusted setting modes names the accounts Work and Personal show, Everything shows every
granted account; /read shows one mail as escaped text with its tasks, promises and attachments as downloads,
records it opened, and offers its corrections (mark and group, not a task, not a promise, read later), each
calling correct. Issue 1850: a sender with no display name is named by its address, on the list, the pane and
All mail.

modules/mesh-mail-web/module.json

@@ -63,6 +63,12 @@
       "description": "The Keycloak identities (the ID token's preferred_username) let to sign in; nobody by default (novox/hq ADR 0440 §3).",
       "trusted": true,
       "default": []
+    },
+    "modes": {
+      "type": "object",
+      "description": "Which mail accounts the mail page's modes Work and Personal each show, by the accounts' names in mail-store, as {\"work\": [...], \"personal\": [...]}; Everything shows every granted account (novox/hq ADR 0515 §4). A mode it names no account for shows nothing and says so.",
+      "trusted": true,
+      "default": {}
     }
   },
   "tools": [
@@ -101,6 +107,17 @@
       "template": "files/operators.json",
       "takes-config": ["operators"]
     },
+    {
+      "id": "modes",
+      "trusted": true,
+      "type": "file",
+      "path": "${dir:state}/modes.json",
+      "mode": "0600",
+      "owner": "mesh-mail-web",
+      "merge": "json",
+      "template": "files/modes.json",
+      "takes-config": ["modes"]
+    },
     {
       "id": "oidc-config",
       "type": "file",
@@ -123,6 +140,7 @@
         "env": {
           "MESH_MAIL_WEB_OPERATORS": "${dir:state}/operators.json",
           "MESH_MAIL_WEB_OIDC": "${dir:state}/oidc.json",
+          "MESH_MAIL_WEB_MODES": "${dir:state}/modes.json",
           "MESH_MAIL_WEB_LISTEN": "${port:8099}"
         }
       },