feat(velocity)!: build against Velocity API 4.0.0 and drop Velocity 3.5.x support

Velocity moved to the 4.x generation while platform-velocity still compiled
against 3.5.1, so the debug environment had to pin an older proxy than the one
most users now run.

The migration needed no source changes. Comparing every one of the 213 classes in
the API jar with javap shows 4.0.0 is identical to 3.5.1 in its public
signatures; the supported protocol range is unchanged too. The one real
difference is the POM, which moves adventure-bom from 4.26.1 to 5.2.0.

Support for 3.5.x is dropped even though the JAR would still load there, because
keeping it meant Adventure 4.26.1 could be the runtime and engine had to stay
inside the API surface both Adventure majors share -- a constraint no build step
could check. Narrowing to 4.x makes every supported runtime ship Adventure 5.2.0,
matching what engine already compiles against, so the constraint is gone rather
than merely documented. Nothing enforces the requirement in code, matching how
dropping 3.4.0 was handled in v1.1.0.

Also drops two dead dependencies: kaml, declared but never imported, worth about
1 MB of shaded JAR, and the velocity-api annotationProcessor, which does nothing
without Java sources or kapt.

3 files changed, 4 insertions, 4 deletions

diff --git a/website/.vitepress/theme/components/DownloadCard.vue b/website/.vitepress/theme/components/DownloadCard.vue
index af54d10..add8d45 100644
--- a/website/.vitepress/theme/components/DownloadCard.vue
+++ b/website/.vitepress/theme/components/DownloadCard.vue
@@ -15,7 +15,7 @@ const t = computed(() =>
         requirements: 'Requirements',
         javaReq: '25 or later',
         paperReq: '26.2.x or later',
-        velocityReq: '3.5.x or later',
+        velocityReq: '4.0.x or later',
         noRelease: 'No release',
         releaseDate: 'Release date',
         fileSize: 'File size',
@@ -45,7 +45,7 @@ const t = computed(() =>
         requirements: '動作要件',
         javaReq: '25 以降',
         paperReq: '26.2.x 以降',
-        velocityReq: '3.5.x 以降',
+        velocityReq: '4.0.x 以降',
         noRelease: 'リリースなし',
         releaseDate: 'リリース日',
         fileSize: 'ファイルサイズ',
diff --git a/website/src/docs/developers/resource.md b/website/src/docs/developers/resource.md
index ccc9eec..1526cf7 100644
--- a/website/src/docs/developers/resource.md
+++ b/website/src/docs/developers/resource.md
@@ -11,7 +11,7 @@ A Gradle multi-module setup shares `engine` while building and releasing Paper /
 - Root `build.gradle.kts` — manages Kotlin 2.4.0 + serialization / Shadow / ktlint / dokka. The JVM target is **JVM_25**. Tests use JUnit Platform + jacoco, with common test dependencies injected into all modules
 - `engine` — exposes core libraries (serialization / coroutines / ktor) via `api()` to propagate them to the platforms. Adventure is `compileOnly`. A pure library with no Shadow
 - `platform-paper` — `version = paperVersion`. `api(project(":engine"))`. paper-api as `compileOnly`, KAML + kotlin-reflect as `implementation`. Output is **`LunaticChat-<ver>.jar`** (no classifier; `jar` disabled)
-- `platform-velocity` — `version = velocityVersion`. `api(project(":engine"))`. velocity-api as `compileOnly` + `annotationProcessor` (for `@Plugin` processing). Output is **`LunaticChat-<ver>-velocity.jar`** (distinguished by classifier)
+- `platform-velocity` — `version = velocityVersion`. `api(project(":engine"))`. velocity-api as `compileOnly`. Output is **`LunaticChat-<ver>-velocity.jar`** (distinguished by classifier)
 - `dokka` — aggregates engine/paper/velocity and includes the README in the HTML
 
 Both platforms' `processResources` compute `version` / `gitCommitHash` / `channel` from the git short hash and `isNightly`, and token-expand them into `paper-plugin.yml` / `velocity-plugin.json` and `build-info.properties`.
diff --git a/website/src/ja/docs/developers/resource.md b/website/src/ja/docs/developers/resource.md
index 78d6128..b06864a 100644
--- a/website/src/ja/docs/developers/resource.md
+++ b/website/src/ja/docs/developers/resource.md
@@ -11,7 +11,7 @@ Gradle マルチモジュール構成で，engine を共有しつつ Paper / Vel
 - ルート `build.gradle.kts` — Kotlin 2.4.0 + serialization / Shadow / ktlint / dokka を管理．JVM ターゲットは **JVM_25**．テストは JUnit Platform + jacoco で，共通テスト依存を全モジュールへ注入
 - `engine` — コアライブラリ (serialization / coroutines / ktor) を `api()` で公開しプラットフォームへ伝播．Adventure は `compileOnly`．Shadow を持たない純ライブラリ
 - `platform-paper` — `version = paperVersion`．`api(project(":engine"))`．paper-api を `compileOnly`，KAML + kotlin-reflect を `implementation`．成果物は **`LunaticChat-<ver>.jar`** (classifier なし，`jar` は無効化)
-- `platform-velocity` — `version = velocityVersion`．`api(project(":engine"))`．velocity-api を `compileOnly` + `annotationProcessor` (`@Plugin` 処理用)．成果物は **`LunaticChat-<ver>-velocity.jar`** (classifier で区別)
+- `platform-velocity` — `version = velocityVersion`．`api(project(":engine"))`．velocity-api を `compileOnly`．成果物は **`LunaticChat-<ver>-velocity.jar`** (classifier で区別)
 - `dokka` — engine/paper/velocity を集約し HTML に README を include
 
 両プラットフォームの `processResources` は git short hash と `isNightly` から `version` / `gitCommitHash` / `channel` を算出し，`paper-plugin.yml` / `velocity-plugin.json` と `build-info.properties` にトークン展開します．