chore: update dependencies and remove unused files

- Replaced `flutter_highlight` with `gpt_markdown` in `pubspec.yaml`.
- Updated `pubspec.lock` to reflect new dependencies and removed obsolete ones.
- Deleted outdated Riverpod migration documentation files to streamline the project.
- Added new configurations for GptMarkdown styling in `markdown_config.dart` and updated the streaming markdown widget implementation.

pubspec.lock

@@ -430,14 +430,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.4.1"
-  flutter_highlight:
-    dependency: "direct main"
-    description:
-      name: flutter_highlight
-      sha256: "7b96333867aa07e122e245c033b8ad622e4e3a42a1a2372cbb098a2541d8782c"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.7.0"
   flutter_lints:
     dependency: "direct dev"
     description:
@@ -451,6 +443,14 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_math_fork:
+    dependency: transitive
+    description:
+      name: flutter_math_fork
+      sha256: "6d5f2f1aa57ae539ffb0a04bb39d2da67af74601d685a161aff7ce5bda5fa407"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.4"
   flutter_native_splash:
     dependency: "direct dev"
     description:
@@ -531,6 +531,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.1.3"
+  flutter_svg:
+    dependency: transitive
+    description:
+      name: flutter_svg
+      sha256: b9c2ad5872518a27507ab432d1fb97e8813b05f0fc693f9d40fad06d073e0678
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.1"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -589,6 +597,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "14.8.1"
+  gpt_markdown:
+    dependency: "direct main"
+    description:
+      name: gpt_markdown
+      sha256: "8174983f2ed7d8576d25810913e3afe3f8ffdaa3172c0c823b7cfc289b67f380"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.4"
   graphs:
     dependency: transitive
     description:
@@ -597,14 +613,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.3.2"
-  highlight:
-    dependency: transitive
-    description:
-      name: highlight
-      sha256: "5353a83ffe3e3eca7df0abfb72dcf3fa66cc56b953728e7113ad4ad88497cf21"
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.7.0"
   hotreloader:
     dependency: transitive
     description:
@@ -797,22 +805,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.3.0"
-  markdown:
-    dependency: transitive
-    description:
-      name: markdown
-      sha256: "935e23e1ff3bc02d390bad4d4be001208ee92cc217cb5b5a6c19bc14aaa318c1"
-      url: "https://pub.dev"
-    source: hosted
-    version: "7.3.0"
-  markdown_widget:
-    dependency: "direct main"
-    description:
-      name: markdown_widget
-      sha256: b52c13d3ee4d0e60c812e15b0593f142a3b8a2003cde1babb271d001a1dbdc1c
-      url: "https://pub.dev"
-    source: hosted
-    version: "2.3.2+8"
   matcher:
     dependency: transitive
     description:
@@ -853,6 +845,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "5.5.0"
+  nested:
+    dependency: transitive
+    description:
+      name: nested
+      sha256: "03bac4c528c64c95c722ec99280375a6f2fc708eec17c7b3f07253b626cd2a20"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
   node_preamble:
     dependency: transitive
     description:
@@ -901,6 +901,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_parsing:
+    dependency: transitive
+    description:
+      name: path_parsing
+      sha256: "883402936929eac138ee0a45da5b0f2c80f89913e6dc3bf77eb65b84b409c6ca"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
   path_provider:
     dependency: "direct main"
     description:
@@ -989,6 +997,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.3"
+  provider:
+    dependency: transitive
+    description:
+      name: provider
+      sha256: "4e82183fa20e5ca25703ead7e05de9e4cceed1fbd1eadc1ac3cb6f565a09f272"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.1.5+1"
   pub_semver:
     dependency: transitive
     description:
@@ -1117,14 +1133,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.28.0"
-  scroll_to_index:
-    dependency: transitive
-    description:
-      name: scroll_to_index
-      sha256: b707546e7500d9f070d63e5acf74fd437ec7eeeb68d3412ef7b0afada0b4f176
-      url: "https://pub.dev"
-    source: hosted
-    version: "3.0.1"
   share_handler:
     dependency: "direct main"
     description:
@@ -1482,6 +1490,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.0.2"
+  tuple:
+    dependency: transitive
+    description:
+      name: tuple
+      sha256: a97ce2013f240b2f3807bcbaf218765b6f301c3eff91092bcfa23a039e7dd151
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.2"
   typed_data:
     dependency: transitive
     description:
@@ -1570,6 +1586,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.5.1"
+  vector_graphics:
+    dependency: transitive
+    description:
+      name: vector_graphics
+      sha256: a4f059dc26fc8295b5921376600a194c4ec7d55e72f2fe4c7d2831e103d461e6
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.19"
+  vector_graphics_codec:
+    dependency: transitive
+    description:
+      name: vector_graphics_codec
+      sha256: "99fd9fbd34d9f9a32efd7b6a6aae14125d8237b10403b422a6a6dfeac2806146"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.13"
+  vector_graphics_compiler:
+    dependency: transitive
+    description:
+      name: vector_graphics_compiler
+      sha256: d354a7ec6931e6047785f4db12a1f61ec3d43b207fc0790f863818543f8ff0dc
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.19"
   vector_math:
     dependency: transitive
     description:
@@ -1578,14 +1618,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.0"
-  visibility_detector:
-    dependency: transitive
-    description:
-      name: visibility_detector
-      sha256: dd5cc11e13494f432d15939c3aa8ae76844c42b723398643ce9addb88a5ed420
-      url: "https://pub.dev"
-    source: hosted
-    version: "0.4.0+2"
   vm_service:
     dependency: transitive
     description: