fix(opencode): prefer monorepo roots for jdtls

[kurochenko]

Summary

• make JDTLS root detection prefer monorepo markers (settings.gradle(.kts)), then wrapper markers (gradlew), and only then nearest module build files
• this prevents spawning one JDTLS process per Gradle module in Java monorepos and keeps a single shared server for a repo
• add root-selection tests covering Groovy Gradle (settings.gradle/build.gradle) and Kotlin DSL (*.kts) cases

Verification

• bun test test/lsp/server-root.test.ts
• bun test test/lsp/*.test.ts

Fixes #11368

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

I found a potentially related PR:

PR #12123: "fix: Multiple jdtls LSPs eating memory in java monorepos"

• fix: Multiple jdtls LSPs eating memory in java monorepos #12123

This PR appears to address the same core issue - preventing multiple JDTLS processes from being spawned in Java monorepos. The current PR (14049) seems to be a continuation or refinement of this work, implementing the specific root detection strategy to solve the issue (#11368) that was likely identified in or related to PR #12123.