update readme and examples

[cs01]

Summary

• Updated README to reflect current compiler maturity (470+ tests, compile-time error coverage)
• Refreshed hero example to show async/await + Promise.all
• Added Map, Set, RegExp, console, ArgumentParser to "what's included" table
• Removed redundant cli-parser-demo.ts (word-count.ts already showcases ArgumentParser)
• Improved query.ts example with GROUP BY aggregation
• Simplified hello.ts
• Updated run-examples.sh (8 tests instead of 9)

Test plan

• 474 unit tests pass
• Prettier formatting passes
• CI green

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