core, ui: per-server roles for self-hosted servers (#7254)

* core, ui: plan per-server roles for self-hosted servers

* core: add per-server roles field to UserServer

* core: add nullable role columns to protocol_servers

* core: persist per-server roles

* core: validate server coverage using per-server roles

* test: cover per-server roles resolution and coverage

* multiplatform: per-server role toggles for self-hosted servers

* ios: per-server role toggles for self-hosted servers

* core: per-server role overrides with per-role defaults

* test: cover three-state per-server role resolution

* fix: derive Eq for ServerRolesOverride

* multiplatform: three-state role dropdowns on saved servers

* ios: three-state role pickers on saved servers

* test: per-server roles independent across two servers

* test: enable names role in name-resolution tests

* style: trim comments in per-server roles code

* chore: rename server_roles migration to 20260716 (last)

* core: per-server roles override operator roles, inherit when unset

* multiplatform: per-server role default inherits from operator

* ios: per-server role default inherits from operator

* refactor(servers): tidy per-server roles per review

- dedup no-operator default into ServerRoles.noOperatorDefault (Kotlin/Swift)
- iOS: move roles-section control flow to the call site via a named gate,
  and parse the server address once instead of up to three times
- Kotlin: collapse redundant derivedState; revert defaultOn->default rename
  for cross-platform parity
- drop unused Hashable conformance on Swift ServerRoles
- add agentServerCfgs test for names inheritance from an operator
- remove no-op enableNamesRole calls from dormant DirectoryTests
- fix ChatClient import ordering

* chore(migration): date server_roles migration 20260720

* only show roles when server is enabled, move section above QR code

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

src/Simplex/Chat/View.hs

@@ -1659,12 +1659,12 @@ viewUserServers UserOperatorServers {operator, smpServers, xftpServers, chatRela
             testedInfo = maybe [] (\t -> ["test: " <> if t then "passed" else "failed"]) tested
         viewRoles op@ServerOperator {enabled}
           | not enabled = "disabled"
-          | storage rs && proxy rs = "enabled"
-          | storage rs = "enabled storage"
-          | proxy rs = "enabled proxy"
+          | rStorage && rProxy = "enabled"
+          | rStorage = "enabled storage"
+          | rProxy = "enabled proxy"
           | otherwise = "disabled (servers known)"
           where
-            rs = operatorRoles p op
+            ServerRoles {storage = rStorage, proxy = rProxy} = operatorRoles p op
     viewChatRelays :: [UserChatRelay] -> [StyledString]
     viewChatRelays [] = []
     viewChatRelays cRelays
@@ -1752,12 +1752,12 @@ viewOpEnabled ServerOperator {enabled, smpRoles, xftpRoles}
   | both smpRoles && both xftpRoles = "enabled"
   | otherwise = "SMP " <> viewRoles smpRoles <> ", XFTP " <> viewRoles xftpRoles
   where
-    no rs = not $ storage rs || proxy rs
-    both rs = storage rs && proxy rs
-    viewRoles rs
+    no ServerRoles {storage, proxy} = not $ storage || proxy
+    both ServerRoles {storage, proxy} = storage && proxy
+    viewRoles rs@ServerRoles {storage, proxy}
       | both rs = "enabled"
-      | storage rs = "enabled storage"
-      | proxy rs = "enabled proxy"
+      | storage = "enabled storage"
+      | proxy = "enabled proxy"
       | otherwise = "disabled (servers known)"
 
 viewConditionsAction :: UsageConditionsAction -> [StyledString]