fix(installer): require provider in quick-start (#1) + local-tier gateway Redis gate (#2)

Bug #1 — quick-start wizard let users skip the LLM provider/API key yet
reported "Mosaic is ready". provider-setup now requires an interactive
provider select + a validated key; quick-start guards the headless path;
finalize won't print "Mosaic is ready" without a configured provider;
removed references to the non-existent `mosaic configure` command.

Bug #2 — the "local" storage tier still opened ioredis/BullMQ
connections at bootstrap (ECONNREFUSED, gateway never healthy). Every
Redis consumer (queue.service, gc.module, session-gc.service,
commands.module, command-executor.service, system-override.service,
cron.service, admin-health.controller) is now tier-aware and degrades
gracefully on local tier. Standalone/Federated unaffected. Also fixed a
pre-existing SystemOverrideService ioredis handle leak (added shutdown hook).

Refs #675

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RMoEx7hfdFGjUiCHuN1RRi

packages/mosaic/__tests__/integration/unified-wizard.test.ts

@@ -69,6 +69,8 @@ describe('Unified wizard (runWizard with default skipGateway)', () => {
 
     const prompter = new HeadlessPrompter({
       'Installation mode': 'quick',
+      'Select your LLM provider': 'anthropic',
+      'Anthropic API key': 'sk-ant-api03-test',
       'What name should agents use?': 'TestBot',
       'Communication style': 'direct',
       'Your name': 'Tester',
@@ -103,6 +105,8 @@ describe('Unified wizard (runWizard with default skipGateway)', () => {
 
     const prompter = new HeadlessPrompter({
       'Installation mode': 'quick',
+      'Select your LLM provider': 'anthropic',
+      'Anthropic API key': 'sk-ant-api03-test',
       'What name should agents use?': 'TestBot',
       'Communication style': 'direct',
       'Your name': 'Tester',
@@ -125,6 +129,8 @@ describe('Unified wizard (runWizard with default skipGateway)', () => {
   it('respects skipGateway: true', async () => {
     const prompter = new HeadlessPrompter({
       'Installation mode': 'quick',
+      'Select your LLM provider': 'anthropic',
+      'Anthropic API key': 'sk-ant-api03-test',
       'What name should agents use?': 'TestBot',
       'Communication style': 'direct',
       'Your name': 'Tester',