feat(sbt): add SBT (Scala Build Tool) support

[randomBrainstormer]

Summary

• Adds rtk sbt test — ScalaTest output filtering with 90% token reduction (compact single-line on pass, failure details on fail)
• Adds rtk sbt compile — strips SBT noise, keeps errors with 75% token reduction (source count + time on success)
• Adds rtk sbt run — light filtering, strips SBT preamble, passes through program output
• Adds rtk sbt <other> — passthrough for any unsupported subcommand

Implementation

Follows the established go_cmd.rs pattern:

• lazy_static! regex for noise/summary/error line detection
• crate::tee::tee_and_hint for full output recovery on failure
• Exit code propagation for CI/CD compatibility
• Discovery rules updated (src/discover/rules.rs) with 80% savings estimate

Test plan

• 11 unit tests with token savings assertions (>=60% on test pass, >=40% on test fail, >=30% on compile error)
• 3 real-output fixtures: sbt_test_pass.txt, sbt_test_fail.txt, sbt_compile_error.txt
• cargo fmt --all --check — clean
• cargo clippy --all-targets — clean
• cargo test --all — 990 passed, 0 failed
• Manual: rtk sbt test in a real Scala project — pending, will validate on a Scala workspace

Documentation

• README.md — added rtk sbt to build commands section and command rewrite table
• CHANGELOG.md — added entry under [Unreleased]

Signed-off-by: Ivan Severino 4858703+randomBrainstormer@users.noreply.github.com

[CLAassistant]

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