Add TypeScript/JavaScript test miner (#128)

[Dimwiddle]

Description

Implement Discovery issue #128 by adding a TypeScript/JavaScript test-function miner and wiring it into the default discovery pipeline.

This change adds:

• TypeScriptTestMiner for it(...), test(...), and it.todo(...) extraction
• describe-block context mapping into TestFunctionMeta.class_name
• language mapping for .ts/.tsx and .js files
• confidence scoring (0.9 for known framework + .spec. filename, otherwise 0.7)
• parse-failure resilience via MinerErrorKind.PARSE_ERROR
• unit tests for extraction, metadata validation, language mapping, and parse-failure behavior
• feature spec updates for the new Story 9 acceptance coverage

Type of Change

• New feature
• Tests
• Documentation update

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Testing

• make lint-fix
• make lint
• make test
• make pre-commit

Related Issues

Closes #128