Upgrade to Detekt 2.0.0-alpha.2 with analysis_mode and fail_on_severity attrs

[ryanulep]

Upgrades the default Detekt version from 1.23.8 to 2.0.0-alpha.2, adapting to the new Detekt 2.x API and CLI changes.

Changes

• Default Detekt version: 1.23.8 → 2.0.0-alpha.2
• Java package: io.gitlab.arturbosch.detekt → dev.detekt
• analysis_mode attr (replaces enable_type_resolution): "light" (default, syntax-only) or "full" (type resolution with classpath)
• fail_on_severity attr: controls minimum severity that fails the build ("Error" default, or "Warning", "Info", "Never")
• Console output: findings now use Detekt's built-in markdown console reporter instead of a text report file; txt_report attr removed
• Toolchain: default language_version updated to 2.3; jvm_target now supports values up to 24
• README: updated compatibility matrix to include v1.0-alpha.2 row; improved documentation throughout

Breaking Changes

• enable_type_resolution attr removed — use analysis_mode = "full" instead
• max_issues attr removed — use fail_on_severity instead
• txt_report attr removed — text report output is no longer supported by Detekt 2.x
• Not compatible with Detekt 1.x; use v0.8.x for Detekt 1.x support

[Bencodes]

Why the package name change here? Maybe unlikely but this could break people that are depending on this via the compiled jar in their own binary target.

[ryanulep]

Detekt v2 changed the namespace so it has to be updated here to invoke the CLI. Otherwise, there's an error when invoking the rule that io.gitlab.arturbosch.detekt.cli.CliRunner does not exist.

[everag]

@ryanulep any updates on this? I've been following this PR in hopes to introduce detekt to a JDK 25 based codebase.