Add a source to all emitted diagnostics (#1491)

Fixes #1490

Screenshots of diagnostics that show the source:
<img width="1148" height="255" alt="Screenshot 2025-11-04 at 10 29 05"
src="https://github.com/user-attachments/assets/9cb4e1df-2fe9-4bf5-a19f-5b08b15ca2d6"
/>
<img width="773" height="148" alt="Screenshot 2025-11-04 at 10 29 16"
src="https://github.com/user-attachments/assets/49fc8273-a489-4e9b-b620-affceac34452"
/>

Author: thecrypticace

packages/tailwindcss-language-server/tests/code-actions/conflict.json

@@ -7,6 +7,7 @@
       "diagnostics": [
         {
           "code": "cssConflict",
+          "source": "tailwindcss",
           "className": {
             "className": "lowercase",
             "classList": {
@@ -85,6 +86,7 @@
       "diagnostics": [
         {
           "code": "cssConflict",
+          "source": "tailwindcss",
           "className": {
             "className": "uppercase",
             "classList": {

packages/tailwindcss-language-server/tests/code-actions/invalid-screen.json

@@ -8,6 +8,7 @@
       "diagnostics": [
         {
           "code": "invalidScreen",
+          "source": "tailwindcss",
           "range": {
             "start": { "line": 0, "character": 8 },
             "end": { "line": 0, "character": 13 }

packages/tailwindcss-language-server/tests/code-actions/invalid-theme.json

@@ -8,6 +8,7 @@
       "diagnostics": [
         {
           "code": "invalidConfigPath",
+          "source": "tailwindcss",
           "range": {
             "start": { "line": 0, "character": 21 },
             "end": { "line": 0, "character": 35 }

packages/tailwindcss-language-server/tests/code-actions/invalid-variant.json

@@ -8,6 +8,7 @@
       "diagnostics": [
         {
           "code": "invalidVariant",
+          "source": "tailwindcss",
           "range": {
             "start": { "line": 0, "character": 10 },
             "end": { "line": 0, "character": 16 }

packages/tailwindcss-language-server/tests/code-actions/variant-order.json

@@ -7,6 +7,7 @@
       "diagnostics": [
         {
           "code": "recommendedVariantOrder",
+          "source": "tailwindcss",
           "suggestions": ["focus:hover:uppercase"],
           "range": {
             "start": { "line": 0, "character": 12 },

packages/tailwindcss-language-server/tests/diagnostics/css-conflict/css.json

@@ -4,6 +4,7 @@
   "expected": [
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "uppercase",
         "classList": {
@@ -59,6 +60,7 @@
     },
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "lowercase",
         "classList": {

packages/tailwindcss-language-server/tests/diagnostics/css-conflict/jsx-concat-positive.json

@@ -4,6 +4,7 @@
   "expected": [
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "lowercase",
         "classList": {
@@ -57,6 +58,7 @@
     },
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "uppercase",
         "classList": {

packages/tailwindcss-language-server/tests/diagnostics/css-conflict/simple.json

@@ -3,6 +3,7 @@
   "expected": [
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "uppercase",
         "classList": {
@@ -56,6 +57,7 @@
     },
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "lowercase",
         "classList": {

packages/tailwindcss-language-server/tests/diagnostics/css-conflict/variants-positive.json

@@ -3,6 +3,7 @@
   "expected": [
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "sm:uppercase",
         "classList": {
@@ -56,6 +57,7 @@
     },
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "sm:lowercase",
         "classList": {

packages/tailwindcss-language-server/tests/diagnostics/css-conflict/vue-style-lang-sass.json

@@ -4,6 +4,7 @@
   "expected": [
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "uppercase",
         "classList": {
@@ -59,6 +60,7 @@
     },
     {
       "code": "cssConflict",
+      "source": "tailwindcss",
       "className": {
         "className": "lowercase",
         "classList": {