chat: CESimplexNameNotFound for name lookup misses

connectPlanName now distinguishes "name not found" from "connection
link is invalid". CEInvalidConnReq's message ("Connection link is
invalid, possibly it was created in a previous version") was
misleading when a user typed @alice.simplex against a database that
simply has no contact by that name.

The two "missing prepared link" cases stay on CEInvalidConnReq —
the lookup found a row but the stored link is unusable, which is
closer to the existing semantics. The two truly-missing cases
(no contact found / no group found) move to CESimplexNameNotFound,
which also surfaces the name back to the client for a precise UX.

src/Simplex/Chat/Controller.hs

@@ -1368,6 +1368,7 @@ data ChatErrorType
   | CEChatNotStopped
   | CEChatStoreChanged
   | CEInvalidConnReq
+  | CESimplexNameNotFound {simplexName :: SimplexNameInfo}
   | CEUnsupportedConnReq
   | CEInvalidChatMessage {connection :: Connection, msgMeta :: Maybe MsgMetaJSON, messageData :: Text, message :: String}
   | CEConnReqMessageProhibited

src/Simplex/Chat/Library/Commands.hs

@@ -4179,7 +4179,7 @@ processChatCommand vr nm = \case
           Just PreparedContact {connLinkToConnect} -> pure (connLinkToConnect, CPContactAddress (CAPKnown ct))
           Nothing -> throwChatError CEInvalidConnReq
         Nothing -> case nameType of
-          NTContact -> throwChatError CEInvalidConnReq
+          NTContact -> throwChatError $ CESimplexNameNotFound ni
           NTPublicGroup -> do
             g_ <- withFastStore $ \db -> getGroupInfoBySimplexName db vr user ni
             case g_ of
@@ -4187,7 +4187,7 @@ processChatCommand vr nm = \case
                 Just PreparedGroup {connLinkToConnect = ccLink} ->
                   pure (ACCL SCMContact ccLink, CPGroupLink (GLPKnown g (BoolDef False) Nothing (ListDef [])))
                 Nothing -> throwChatError CEInvalidConnReq
-              Nothing -> throwChatError CEInvalidConnReq
+              Nothing -> throwChatError $ CESimplexNameNotFound ni
     connectWithPlan :: User -> IncognitoEnabled -> ACreatedConnLink -> ConnectionPlan -> CM ChatResponse
     connectWithPlan user@User {userId} incognito ccLink plan
       | connectionPlanProceed plan = do

src/Simplex/Chat/View.hs

@@ -2625,6 +2625,7 @@ viewChatError isCmd logLevel testView = \case
     CEChatNotStopped -> ["error: chat not stopped"]
     CEChatStoreChanged -> ["error: chat store changed, please restart chat"]
     CEInvalidConnReq -> viewInvalidConnReq
+    CESimplexNameNotFound ni -> ["no contact or group with simplex name " <> plain (T.unpack (shortNameInfoStr ni))]
     CEUnsupportedConnReq -> [ "", "Connection link is not supported by the your app version, please ugrade it.", plain updateStr]
     CEInvalidChatMessage Connection {connId} msgMeta_ msg e ->
       [ plain $