[deps]: Update tailwindcss to v4 (#145)

* change SCSS -> CSS per Tailwind v4 recommendation
* run Tailwind v4 upgrade util to migrate existing styles
* add `postcss` dependencies per v4 install instructions
* removed autoprefixer which is not required with v4
* removed unused Bootstrap styles from AppComponent (alert, alert-danger, etc)
* added ShadowDom isolation to main component to avoid Splunk's own
  Bootstrap styling from interfering

Author: renovate[bot]

ui/.postcssrc.json

@@ -0,0 +1,5 @@
+{
+  "plugins": {
+    "@tailwindcss/postcss": {}
+  }
+}

ui/angular.json

@@ -5,11 +5,7 @@
   "projects": {
     "setup": {
       "projectType": "application",
-      "schematics": {
-        "@schematics/angular:component": {
-          "style": "scss"
-        }
-      },
+      "schematics": { "@schematics/angular:component": { "style": "scss" } },
       "root": "",
       "sourceRoot": "src",
       "prefix": "app",
@@ -23,20 +19,13 @@
             "polyfills": ["zone.js"],
             "tsConfig": "tsconfig.app.json",
             "inlineStyleLanguage": "scss",
-            "assets": [
-              {
-                "glob": "**/*",
-                "input": "public"
-              }
-            ],
-            "styles": ["src/styles.scss"],
+            "assets": [{ "glob": "**/*", "input": "public" }],
+            "styles": ["src/styles.css"],
             "scripts": ["node_modules/splunk-sdk/client/splunk.min.js"],
             "outputHashing": "none"
           },
           "configurations": {
-            "production": {
-              "optimization": true
-            },
+            "production": { "optimization": true },
             "development": {
               "optimization": false,
               "extractLicenses": false,
@@ -58,12 +47,8 @@
         "serve": {
           "builder": "@angular-devkit/build-angular:dev-server",
           "configurations": {
-            "production": {
-              "buildTarget": "setup:build:production"
-            },
-            "development": {
-              "buildTarget": "setup:build:development"
-            }
+            "production": { "buildTarget": "setup:build:production" },
+            "development": { "buildTarget": "setup:build:development" }
           },
           "defaultConfiguration": "development"
         },
@@ -76,46 +61,23 @@
             "polyfills": ["zone.js", "zone.js/testing"],
             "tsConfig": "tsconfig.spec.json",
             "inlineStyleLanguage": "scss",
-            "assets": [
-              {
-                "glob": "**/*",
-                "input": "public"
-              }
-            ],
-            "styles": ["src/styles.scss"],
+            "assets": [{ "glob": "**/*", "input": "public" }],
+            "styles": ["src/styles.css"],
             "scripts": []
           }
         }
       }
     }
   },
-  "cli": {
-    "analytics": false
-  },
+  "cli": { "analytics": false },
   "schematics": {
-    "@schematics/angular:component": {
-      "type": "component"
-    },
-    "@schematics/angular:directive": {
-      "type": "directive"
-    },
-    "@schematics/angular:service": {
-      "type": "service"
-    },
-    "@schematics/angular:guard": {
-      "typeSeparator": "."
-    },
-    "@schematics/angular:interceptor": {
-      "typeSeparator": "."
-    },
-    "@schematics/angular:module": {
-      "typeSeparator": "."
-    },
-    "@schematics/angular:pipe": {
-      "typeSeparator": "."
-    },
-    "@schematics/angular:resolver": {
-      "typeSeparator": "."
-    }
+    "@schematics/angular:component": { "type": "component" },
+    "@schematics/angular:directive": { "type": "directive" },
+    "@schematics/angular:service": { "type": "service" },
+    "@schematics/angular:guard": { "typeSeparator": "." },
+    "@schematics/angular:interceptor": { "typeSeparator": "." },
+    "@schematics/angular:module": { "typeSeparator": "." },
+    "@schematics/angular:pipe": { "typeSeparator": "." },
+    "@schematics/angular:resolver": { "typeSeparator": "." }
   }
 }