chore(main): release 1.20.0

[github-actions]

🤖 I have created a release beep boop

1.20.0 (2026-07-17)

Features

• show all model checker messages, including on nodes without a visible cell (44fa9c0)
• show model checker errors in the projectional editor (82a53e0)
• underline the whole cell range of a node-level check message (8ef4663)

Bug Fixes

• deps: update commitlint monorepo to v20.5.3 (#542) (f8bd041)
• deps: update dependency org.jetbrains.kotlinx:kotlinx-collections-immutable to v0.5.1 (#544) (04adf6b)
• don't shift line text when the gutter marks an error or warning (3dbcc22)
• don't underline indentation inside a message's cell range (1926f0a)
• eliminate false model checker errors from wrapper node identity (3af3e93)
• implement FlagCellTemplate.getInstantiationActions (b2d2066)
• make ModelixNodeAsMPSNode a real jetbrains.mps.smodel.SNode (8882f03)
• model checker failed on nodes wrapped as MPS nodes (dd14925)

Performance Improvements

• more fine-grained caching in IncrementalModelChecker (945cf5c)

Code Refactoring

• attach each check message to a single cell; underline the range while rendering (bacfc87)
• remove unused helpers from IncrementalModelChecker (2844109)

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