chore: modernize CI and update Go toolchain

- Bump Go from 1.19 to 1.26 and update all dependencies
- Rewrite CI workflow with matrix strategy (Linux, macOS, Windows)
- Update GitHub Actions to current versions (checkout@v4, setup-go@v5)
- Update CodeQL actions from v1 to v3
- Fix cross-platform bug in mock/path.go (path.Join -> filepath.Join)
- Clean up dependabot config (weekly schedule, remove stale ignore)

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

vendor/github.com/alecthomas/chroma/v2/lexers/embedded/haskell.xml

@@ -86,7 +86,7 @@
       <rule pattern="\\(?![:!#$%&amp;*+.\\/&lt;=&gt;?@^|~-]+)">
         <token type="NameFunction"/>
       </rule>
-      <rule pattern="(&lt;-|::|-&gt;|=&gt;|=)(?![:!#$%&amp;*+.\\/&lt;=&gt;?@^|~-]+)">
+      <rule pattern="(&lt;-|::|-&gt;|=&gt;|=|'([:!#$%&amp;*+.\\/&lt;=&gt;?@^|~-]+))(?![:!#$%&amp;*+.\\/&lt;=&gt;?@^|~-]+)">
         <token type="OperatorWord"/>
       </rule>
       <rule pattern=":[:!#$%&amp;*+.\\/&lt;=&gt;?@^|~-]*">
@@ -95,19 +95,22 @@
       <rule pattern="[:!#$%&amp;*+.\\/&lt;=&gt;?@^|~-]+">
         <token type="Operator"/>
       </rule>
-      <rule pattern="\d+[eE][+-]?\d+">
+      <rule pattern="\d+_*[eE][+-]?\d+">
         <token type="LiteralNumberFloat"/>
       </rule>
-      <rule pattern="\d+\.\d+([eE][+-]?\d+)?">
+      <rule pattern="\d+(_+[\d]+)*\.\d+(_+[\d]+)*([eE][+-]?\d+)?">
         <token type="LiteralNumberFloat"/>
       </rule>
-      <rule pattern="0[oO][0-7]+">
+      <rule pattern="0[oO](_*[0-7])+">
         <token type="LiteralNumberOct"/>
       </rule>
-      <rule pattern="0[xX][\da-fA-F]+">
+      <rule pattern="0[xX](_*[\da-fA-F])+">
         <token type="LiteralNumberHex"/>
       </rule>
-      <rule pattern="\d+">
+      <rule pattern="0[bB](_*[01])+">
+        <token type="LiteralNumberBin"/>
+      </rule>
+      <rule pattern="\d+(_*[\d])*">
         <token type="LiteralNumberInteger"/>
       </rule>
       <rule pattern="&#39;">