fix: differentiate Conex (linkedEntryIds) vs Inchide (threadParentId) semantics

- Conex button now adds to linkedEntryIds (for clarificari/solicitari)
  instead of setting threadParentId
- Inchide button sets threadParentId (direct reply) + auto-closes parent
- Fix Sterge button persistence bug: threadParentId now saves as empty
  string instead of undefined (which was stripped in JSON serialization)
- Card headers: "Conex cu X" (amber) vs "Raspuns la X" (blue + green)
- Add conexTo prop to RegistryEntryForm for linked entry pre-fill

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/modules/registratura/components/registry-entry-form.tsx

@@ -87,8 +87,10 @@ import { getDeadlineType } from "../services/deadline-catalog";
 
 interface RegistryEntryFormProps {
   initial?: RegistryEntry;
-  /** Pre-fill as reply (conex) to this entry — sets threadParentId, flips direction */
+  /** Pre-fill as reply to this entry — sets threadParentId, flips direction (used by "Inchide") */
   replyTo?: RegistryEntry;
+  /** Pre-fill as related/conex entry — adds to linkedEntryIds, keeps direction (used by "Conex") */
+  conexTo?: RegistryEntry;
   allEntries?: RegistryEntry[];
   onSubmit: (
     data: Omit<RegistryEntry, "id" | "number" | "createdAt" | "updatedAt">,
@@ -109,6 +111,7 @@ interface RegistryEntryFormProps {
 export function RegistryEntryForm({
   initial,
   replyTo,
+  conexTo,
   allEntries,
   onSubmit,
   onCancel,
@@ -193,7 +196,7 @@ export function RegistryEntryForm({
   );
   const [notes, setNotes] = useState(initial?.notes ?? "");
   const [linkedEntryIds, setLinkedEntryIds] = useState<string[]>(
-    initial?.linkedEntryIds ?? [],
+    initial?.linkedEntryIds ?? (conexTo ? [conexTo.id] : []),
   );
   const [attachments, setAttachments] = useState<RegistryAttachment[]>(
     initial?.attachments ?? [],
@@ -557,7 +560,7 @@ export function RegistryEntryForm({
         deadline: deadline || undefined,
         assignee: assignee || undefined,
         assigneeContactId: assigneeContactId || undefined,
-        threadParentId: threadParentId || undefined,
+        threadParentId: threadParentId || "",
         recipientRegNumber: recipientRegNumber || undefined,
         recipientRegDate: recipientRegDate || undefined,
         expiryDate: expiryDate || undefined,