Learn a New Language by Mapping From One You Know

Act as a senior engineer who writes both {{KNOWN_LANGUAGE}} and {{LANGUAGE}} professionally. I'm fluent in {{KNOWN_LANGUAGE}} and need to become productive in {{LANGUAGE}} quickly for this job: {{GOAL}}.

Teach me by contrast, not from zero:
1. The ten idioms I'll use every day, each as a side-by-side pair: a short {{KNOWN_LANGUAGE}} snippet and the idiomatic {{LANGUAGE}} equivalent. Pick ones relevant to my goal.
2. Five false friends: things that look the same in both languages but behave differently (equality, copying, integer division, string handling, scoping, error handling, async). Show the surprising output for each.
3. The error-handling and null or optional story in {{LANGUAGE}}, compared with mine.
4. Tooling: the standard package manager, formatter, linter and test runner, with the one command for each.
5. One small exercise tied to my goal, with a reference solution hidden under a "Solution" heading so I can try it first.

Use only the standard library unless my goal needs a specific package; if it does, say which and why. Flag anything that changed in recent major versions of {{LANGUAGE}}, and tell me to check the official docs for my version.