build(261): add IntelliJ IDEA 2026.1 build target

[a1flecke]

Summary

Adds IDE profile for IntelliJ IDEA 2026.1 (build 261.*) to resolve plugin incompatibility with the latest IDE release.

Fixes #6324

Changes

• isUnifiedIde() helper: Replaces 11 scattered startsWith("2025.3") / contains("253") checks with a future-proof version comparison (>= 253). Next IDE releases won't require updating these checks.
• 2026.1 profile in IdeVersions.kt with stable SDK and marketplace plugin versions
• kotlinx-coroutines updated to 1.10.2-intellij-1 for build 261
• Kotlin API target extended to cover 2026.1
• Rider build script updated for rd-gen 2026.1.3 API changes (hashFolder/sources() removed, SystemInfo import path changed)
• Code With Me → Remote Development plugin rename in 2026.1 bundled plugins
• PyAddSdkPanel removal: Moved PyCharmSdkUtil.kt to src-243-253/ (API removed in 2026.1)
• TreeVisitor.Acceptor.accept() nullability change: Added src-261+/S3TreeTableModel.kt with updated return type

Known limitations

• Gateway: JetBrains Gateway 2026.1 DMG extraction on macOS may fail during Gradle transforms (pre-existing macOS issue)
• Rider generateModels: rd-gen 2026.1.3 changed model compilation approach — needs further investigation for full Rider support

Testing

• Core modules (plugin-core, plugin-toolkit:jetbrains-core, plugin-amazonq) compile successfully against IntelliJ IDEA 2026.1
• Project configuration passes for all modules including Rider and Gateway
• isUnifiedIde() has parameterized unit tests covering boundary cases

Test plan

• CI passes for core module compilation against 2026.1
• Plugin installs without "incompatible" warning in IntelliJ IDEA 2026.1
• Existing 2025.3 profile still works (verify ideProfileName=2025.3 builds)

[jacobthompsonramsey]

I'm seeing this issue as well in IntelliJ 2026.1 261*

[diadev]

It would be great to get this in for 261* soon. I've come to rely on it for testing in IntelliJ.

[warrenonedge]

What is the usual turn around time for these updates? I updated my intellij and now i cant' use the tool for my development.

[JustinHarshbarger]

It would be great if we could have a quick turnaround on these plugin issues! The AWS plugins are the only ones I consistently have problems with regarding compatibility after IDEA updates.

[mattsnow]

Same issue, this must be one of the most widely used plugins in IntelliJ. A quick fix would be appreciated

[devurandom]

Closes: #6323

[a1flecke]

Anything else needed to get this over the line?

[warrenonedge]

Commenting again in the hopes that the reviewers who have write permissions see this and approve.

[chriswangsanata-sm]

Bumping

[branrin]

Hi AWS service team has a fix for this in progress and will include it in our release next week to support 2026.1. Thank you for your patience

[warrenonedge]

Hi AWS service team has a fix for this in progress and will include it in our release next week to support 2026.1. Thank you for your patience

Any particular target date? Im stuck in the mud ATM.

[branrin]

Any particular target date? Im stuck in the mud ATM.

The team is targeting Thursday, April 9 release. It is being treated as high priority so if the fix for this and other issues are fully implemented/validated before then it could be released sooner