fix: QA — add missing translation namespaces + fix sharedWithMe dead path

- Add 'signatures' translation namespace (27 keys) to locales
- Add 'settings.tabs.signatures' translation key
- Add 'settings.importer' translation namespace (18 keys)
- Fix sharedWithMe never populated in sharing-store — now discovers
  incoming mail/calendar/addressBook shares by checking isShared+myRights

stores/sharing-store.ts

@@ -258,6 +258,21 @@ export const useSharingStore = create<SharingState>((set, get) => ({
               });
             }
           }
+          if (mb.isShared && mb.myRights) {
+            withMe.push({
+              id: `mb-withme-${mb.id}`,
+              resourceId: mb.id,
+              resourceName: mb.name,
+              resourceKind: "mailbox",
+              principalId: mb.accountId || "unknown",
+              principalName: mb.accountName || "Unknown",
+              principalEmail: null,
+              role: roleLabel("mailbox", detectMailboxPreset(mb.myRights)),
+              direction: "withMe",
+              pending: false,
+              accountId: mb.accountId,
+            });
+          }
         }
       } catch {
         /* mailboxes may not be available */
@@ -286,6 +301,21 @@ export const useSharingStore = create<SharingState>((set, get) => ({
                 });
               }
             }
+            if (cal.isShared && cal.myRights) {
+              withMe.push({
+                id: `cal-withme-${cal.id}`,
+                resourceId: cal.id,
+                resourceName: cal.name,
+                resourceKind: "calendar",
+                principalId: cal.accountId || "unknown",
+                principalName: cal.accountName || "Unknown",
+                principalEmail: null,
+                role: roleLabel("calendar", detectCalendarPreset(cal.myRights)),
+                direction: "withMe",
+                pending: false,
+                accountId: cal.accountId,
+              });
+            }
           }
         }
       } catch {
@@ -318,6 +348,21 @@ export const useSharingStore = create<SharingState>((set, get) => ({
                 });
               }
             }
+            if (book.isShared && book.myRights) {
+              withMe.push({
+                id: `ab-withme-${book.id}`,
+                resourceId: book.id,
+                resourceName: book.name,
+                resourceKind: "addressBook",
+                principalId: book.accountId || "unknown",
+                principalName: book.accountName || "Unknown",
+                principalEmail: null,
+                role: roleLabel("addressBook", detectAddressBookPreset(book.myRights)),
+                direction: "withMe",
+                pending: false,
+                accountId: book.accountId,
+              });
+            }
           }
         }
       } catch {