Bug/alt 11011

[Tsyklop]

This PR addresses critical issues project opening (ALT-11011). modernizes the project opening logic to align with the latest IntelliJ Platform APIs.

🏗 Platform & API Updates

• API Modernization: Refactored OpenProjectTaskCompat to use the latest lambda-based constructor for OpenProjectTask, removing deprecated property assignments.
• Dependency Refresh: Updated gradle-261.properties to target the latest stable IDE versions (IU-2026.1.1, CL-2026.1.1, etc.).

[meanmail]

Overview

The PR updates OpenProjectTaskCompat for the 261 platform branch and bumps IDE versions from EAP/RC to stable releases. The key behavioral changes are setting useDefaultProjectAsTemplate = false and runConversionBeforeOpen = false.

Comments

1. useDefaultProjectAsTemplate and runConversionBeforeOpen changes — these appear to be the actual fix for ALT-11011. Worth noting: the 252/253 branches use the lambda builder and don't explicitly set these properties, so they get whatever the builder defaults to. If the builder defaults differ from false, the behavior may be inconsistent across platform versions. Please verify.

2. beforeInit simplification — good cleanup, removing the redundant wrapper lambda.

3. preparedToOpen cleanup — the null-check pattern is now cleaner and consistent with the intent.

4. Positional constructor retained for 261 — the previous commit switched to the lambda builder (matching 252/253), but this commit reverts to the positional constructor. Is there a specific reason? The lambda builder is more maintainable (no need to specify every parameter).

5. IDE version updates — moving from EAP snapshots to stable 2026.1.x releases is good.