fix(tests): add plugin warm-up to regression spec before() hooks

The monitoring-console-plugin registers the Incidents tab extension
asynchronously after Cypress session restoration. Without warm-up,
the tab may not be registered before beforeEach() tries to navigate,
causing flaky failures in reg/02-05 specs.

Uses warmUpForPlugin() (added in previous commit) which polls for
the Incidents tab via jQuery check for up to 3 minutes — replacing
the fragile goTo() that relied on the 80s default command timeout.

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

Author: Claude Agent

web/cypress/e2e/incidents/regression/02.reg_ui_charts_comprehensive.cy.ts

@@ -103,6 +103,7 @@ const MP = {
 describe('Regression: Charts UI - Comprehensive', { tags: ['@incidents'] }, () => {
   before(() => {
     cy.beforeBlockCOO(MCP, MP, { dashboards: false, troubleshootingPanel: false });
+    incidentsPage.warmUpForPlugin();
   });
 
   beforeEach(() => {

web/cypress/e2e/incidents/regression/03.reg_api_calls.cy.ts

@@ -34,6 +34,7 @@ const MP = {
 describe('Regression: Silences Not Applied Correctly', { tags: ['@incidents'] }, () => {
   before(() => {
     cy.beforeBlockCOO(MCP, MP, { dashboards: false, troubleshootingPanel: false });
+    incidentsPage.warmUpForPlugin();
   });
 
   beforeEach(() => {

web/cypress/e2e/incidents/regression/04.reg_redux_effects.cy.ts

@@ -33,6 +33,7 @@ const MP = {
 describe('Regression: Redux State Management', { tags: ['@incidents', '@incidents-redux'] }, () => {
   before(() => {
     cy.beforeBlockCOO(MCP, MP, { dashboards: false, troubleshootingPanel: false });
+    incidentsPage.warmUpForPlugin();
   });
 
   beforeEach(() => {

web/cypress/e2e/incidents/regression/05.reg_stress_testing_ui.cy.ts

@@ -34,6 +34,7 @@ const MAX_GAP_RELAXED = 500;
 describe('Regression: Stress Testing UI', { tags: ['@incidents'] }, () => {
   before(() => {
     cy.beforeBlockCOO(MCP, MP, { dashboards: false, troubleshootingPanel: false });
+    incidentsPage.warmUpForPlugin();
   });
 
   it('5.1 No excessive padding between chart top and alert bars for 100, 200, and 500 alerts', () => {