fix(cli)(sphere-sdk#282): route wallet use confirmation to STDERR

Residual #2 of the §D `manual-test-full-recovery.sh` ALL GREEN
campaign. The `sphere wallet use <name>` subcommand printed its
confirmation lines

  ✓ Switched to wallet profile: <name>
    Nametag:  <tag>
    L1 Addr:  <alpha1...>

via `console.log` (stdout). The harness captures `sphere balance >
file` snapshots; some snapshot blocks bracket the `wallet use`
invocation outside the redirect (peer2: `sphere wallet use alice ;
sphere balance > file`), others inside a subshell (peer1: `( …
sphere wallet use alice && sphere balance ) > file`). The two
flows yield different captured-stdout content for the same logical
operation, so the resulting peer1-vs-peer2 diff failed assertion
even though both wallets had identical balances.

Fix: route the entire confirmation block (success and `(wallet not
initialized in this profile)` fallback) through `console.error`.
Errors (usage hint, profile-not-found) were already on stderr, so
this brings the success path in line with them. Behaviour for human
operators is unchanged — terminal sessions still see the banner;
only `>` / `|` stdout pipelines are now unaffected by it.

Side-benefit: any future shell tooling that pipes
`sphere wallet use <name> | …` no longer has to filter the banner
out of the consumed stream.

Tests
  * `test/integration/cli-wallet-profile.integration.test.ts` —
    the "`wallet use alice` switches the active profile" assertion
    now expects the banner on `r.stderr` (with a negative match on
    `r.stdout`) per the new contract.
  * Full integration suite: 25 / 25 passed.
  * Full default unit suite: 119 / 119 passed.

Refs sphere-sdk#282

Author: Vladimir Rogojin

src/legacy/legacy-cli.ts

@@ -1982,19 +1982,29 @@ async function main(): Promise<void> {
             }
 
             if (switchToProfile(profileName)) {
-              console.log(`✓ Switched to wallet profile: ${profileName}`);
+              // Issue sphere-sdk#282 Residual #2 — confirmation output
+              // goes to STDERR so that pipelines capturing the NEXT
+              // command's stdout (e.g. `sphere wallet use alice &&
+              // sphere balance > file`) don't accidentally include the
+              // wallet-use banner in the captured snapshot. Without
+              // this, the same logical command sequence produces
+              // different captured-stdout content depending on whether
+              // the harness redirects the `wallet use` invocation
+              // separately or groups it in a subshell — see the
+              // peer1-vs-peer2 asymmetry in `manual-test-full-recovery.sh`.
+              console.error(`✓ Switched to wallet profile: ${profileName}`);
 
               // Show wallet status
               try {
                 const sphere = await getSphere();
                 const identity = sphere.identity;
                 if (identity) {
-                  console.log(`  Nametag:  ${identity.nametag || '(not set)'}`);
-                  console.log(`  L1 Addr:  ${identity.l1Address}`);
+                  console.error(`  Nametag:  ${identity.nametag || '(not set)'}`);
+                  console.error(`  L1 Addr:  ${identity.l1Address}`);
                 }
                 await closeSphere();
               } catch {
-                console.log('  (wallet not initialized in this profile)');
+                console.error('  (wallet not initialized in this profile)');
               }
             } else {
               console.error(`Profile "${profileName}" not found.`);

test/integration/cli-wallet-profile.integration.test.ts

@@ -230,7 +230,11 @@ describe('sphere-cli — wallet profile CRUD lifecycle (offline)', () => {
   it('`wallet use alice` switches the active profile', () => {
     const r = runSphere(env, ['wallet', 'use', 'alice'], { timeoutMs: 15_000 });
     expect(r.status).toBe(0);
-    expect(r.stdout).toMatch(/Switched to wallet profile:\s*alice/);
+    // sphere-sdk#282 Residual #2 — confirmation lives on STDERR so
+    // downstream `sphere wallet use … && sphere balance > file` shell
+    // pipelines don't fold the banner into the captured snapshot.
+    expect(r.stderr).toMatch(/Switched to wallet profile:\s*alice/);
+    expect(r.stdout).not.toMatch(/Switched to wallet profile/);
 
     // Verify by re-reading current.
     const current = runSphere(env, ['wallet', 'current'], { timeoutMs: 15_000 });