diag(nip46): add temporary lifecycle diagnostics for #33

Code-level audit of the NIP-46/Amber login+profile+persistence bug points at a
single shared SignerManager.nip46Client + per-profile restore/switch not being
multi-account-aware. Added TEMP [nip46-diag] userLogger traces (visible on
unstable; devLogger is gated off there) at:
- scheduleStoredRemoteSignerRestore (restore-on-load → "unknown user")
- disconnectRemoteSigner (the shared-client teardown → "logs out everyone")
- SignerManager.logout (scope)
- authService.switchProfile (does the switch resolve the expected pubkey)

These let a single Amber reproduction pinpoint the exact failure before the fix.
Findings + plan recorded under TODO #33. Remove diagnostics with the fix.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

js/services/authService.js

@@ -977,6 +977,12 @@ export default class AuthService {
     const providerId = normalizeProviderId(normalizedOptions.providerId);
 
     const normalizedActive = this.normalizeHexPubkey(getActiveProfilePubkey());
+    // [nip46-diag] TEMP (todo #33): trace profile switching — from/to + provider.
+    userLogger.info("[nip46-diag] switchProfile: begin", {
+      from: normalizedActive || null,
+      to: normalizedTarget,
+      providerId: providerId || null,
+    });
     if (normalizedActive && normalizedActive === normalizedTarget) {
       return { switched: false, reason: "already-active" };
     }
@@ -993,6 +999,10 @@ export default class AuthService {
     try {
       requestResult = await this.requestLogin(requestOptions);
     } catch (error) {
+      userLogger.warn("[nip46-diag] switchProfile: requestLogin FAILED", {
+        to: normalizedTarget,
+        message: error?.message || String(error),
+      });
       throw error;
     }
 
@@ -1001,6 +1011,13 @@ export default class AuthService {
       (typeof requestResult?.pubkey === "string"
         ? requestResult.pubkey.trim()
         : "");
+    // [nip46-diag] TEMP (todo #33): did the switch resolve the EXPECTED pubkey?
+    userLogger.info("[nip46-diag] switchProfile: requestLogin returned", {
+      to: normalizedTarget,
+      requestedPubkey: requestedPubkey || null,
+      matchesTarget: requestedPubkey === normalizedTarget,
+      hasDetail: !!requestResult?.detail,
+    });
 
     let detail = requestResult?.detail || null;