Bump version to v4.0.0

Major release. Krill metadata field names were corrected by default in
this cycle (textClass -> dmozDomain, textDomain -> idsColumn), which
changes the emitted index field names unless --legacy-field-names is
passed; hence the major version bump. Also includes the Krill empty-text
drop (#46), the tokenSource stand-off fix (#48), externalLink derivation
for Wikipedia/DGD/Süddeutsche/Genios (#47), and the custom-tokenization
and sentence-segmentation fallbacks for TEI-converted corpora.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Change-Id: I242758abdaa37a3dd76f4ed826c3e05006bdd12c
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5b4233c..70aa5f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 # Changelog
 
-## [Unreleased]
+## [v4.0.0] - 2026-06-12
 
 ### Added
 
@@ -21,6 +21,7 @@
 ### Changed
 
 - Krill metadata field names corrected by default: the misleadingly named `textClass` is now emitted as `dmozDomain` (DMOZ-based topic-domain classification) and `textDomain` as `idsColumn` (normalised newspaper column / Ressort). Pass `--legacy-field-names` to keep the historical names. Note: querying the corrected indices by the old names will require a need an accordingly configured Koral Mapper plugin to be active.
+- Dependency updates: `org.apache.opennlp:opennlp-tools` 2.5.7 → 2.5.8, `com.google.guava:guava` 33.5.0-jre → 33.6.0-jre, `org.apache.ant:ant` 1.10.15 → 1.10.17, `org.jetbrains.kotlin:kotlin-test` 2.3.20 → 2.3.21, and the `softprops/action-gh-release` GitHub Action 2 → 3.
 
 ## [v3.4.0] - 2026-06-08
 
diff --git a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt
index d3e3b39..c0e9074 100644
--- a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt
+++ b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt
@@ -61,7 +61,7 @@
 @Command(
     name = "korapxmltool",
     mixinStandardHelpOptions = true,
-    version = ["korapxmltool v3.4.0"],
+    version = ["korapxmltool v4.0.0"],
     usageHelpAutoWidth = false,
     usageHelpWidth = 200,
     description = ["Converts between KorAP-XML ZIP format and formats like CoNLL-U, Krill, word2vec, NOW\n"+
diff --git a/build.gradle b/build.gradle
index 6ebe5dd..3b3c750 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,4 +5,4 @@
 }
 
 // Zentrale Projektversion für korapxmltool
-version = '3.4.0'
+version = '4.0.0'