Fix docs gulp race condition with parallel builds

Replace the deep `**` glob pattern for DSL docs with explicit depth
patterns using `!(target)` extglob to structurally prevent entering
target/ directories during directory scanning.

Add a resilientSrc() wrapper around gulp.src() that gracefully handles
ENOENT errors from ephemeral directories (e.g. .camel-jbang/work
created/deleted by parallel JBang tests). The wrapper continues
processing remaining files instead of aborting the entire stream,
and uses a close event handler as fallback to prevent task hangs.

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

Author: gnodet

docs/gulpfile.js

@@ -206,7 +206,8 @@ const sources = {
         '../core/camel-base/src/main/docs/!(*-component|*-language|*-dataformat|*-summary).adoc',
         '../core/camel-main/src/main/docs/!(*-component|*-language|*-dataformat|*-summary).adoc',
         '../components/{*,*/*}/src/main/docs/!(*-component|*-language|*-dataformat|*-summary).adoc',
-        '../dsl/**/src/main/docs/!(*-component|*-language|*-dataformat|*-summary).adoc',
+        '../dsl/src/main/docs/!(*-component|*-language|*-dataformat|*-summary).adoc',
+        '../dsl/{*,*/!(target)}/src/main/docs/!(*-component|*-language|*-dataformat|*-summary).adoc',
       ],
       destination: 'components/modules/others/pages',
       keep: [
@@ -314,6 +315,37 @@ const tasks = Array.from(sourcesMap).flatMap(([type, definition]) => {
     })
   }
 
+  // Wraps gulp.src to gracefully handle ENOENT from ephemeral directories
+  // (e.g. .camel-jbang/work created/deleted by tests running in parallel).
+  // We pipe through a passthrough transform so that on ENOENT we can
+  // cleanly end() the passthrough, which properly signals downstream
+  // pipes to finish. Direct error handling on gulp.src() doesn't work
+  // because Node.js .pipe() does not propagate errors or end signals.
+  const ignorePatterns = ['**/target/**', '**/.camel-jbang/**']
+  const resilientSrc = (source, options) => {
+    const src = gulp.src(source, options)
+    const passthrough = through2.obj(function (file, enc, done) {
+      done(null, file)
+    })
+    src.on('error', function (err) {
+      if (err.code === 'ENOENT') {
+        // Don't end passthrough — the source may continue with remaining files.
+        // If it stops, the 'close' handler below will clean up.
+        console.error(`⚠️ ENOENT (skipped): ${err.path || err.message}`)
+      } else {
+        passthrough.destroy(err)
+      }
+    })
+    // If the source closes without emitting 'end' (e.g. after an error),
+    // ensure the passthrough ends so downstream tasks don't hang.
+    src.on('close', function () {
+      if (!passthrough.writableEnded) {
+        passthrough.end()
+      }
+    })
+    return src.pipe(passthrough)
+  }
+
   // creates symlinks from source to destination that satisfy the
   // given filter removing the basedir from a path, i.e. symlinking
   // from a flat hiearchy
@@ -326,10 +358,12 @@ const tasks = Array.from(sourcesMap).flatMap(([type, definition]) => {
       }
     })
 
-    return gulp.src(source, { ignore: ['**/target/**'] })
+    let fileCount = 0
+    return resilientSrc(source, { ignore: ignorePatterns, allowEmpty: true })
       .pipe(filterFn)
       .pipe(
         map((file, done) => {
+          fileCount++
           // this flattens the output to just .../pages/.../file.ext
           // instead of .../pages/camel-.../src/main/docs/.../file.ext
           file.base = path.dirname(file.path)
@@ -339,6 +373,9 @@ const tasks = Array.from(sourcesMap).flatMap(([type, definition]) => {
       .pipe(gulp.symlink(destination, {
         relativeSymlinks: true,
       }))
+      .on('end', () => {
+        console.log(`  → symlinked ${fileCount} files to ${destination}`)
+      })
   }
 
   // generates sorted & grouped nav.adoc file from a set of .adoc
@@ -409,7 +446,7 @@ const tasks = Array.from(sourcesMap).flatMap(([type, definition]) => {
       return done()
     }
 
-    return gulp.src(source, { ignore: ['**/target/**'] }) // asciidoc files
+    return resilientSrc(source, { ignore: ignorePatterns, allowEmpty: true }) // asciidoc files
       .pipe(through2.obj(extractExamples)) // extracted example files
       // symlink links from a fixed directory, i.e. we could link to
       // the example files from `destination`, that would not work for