🧹 Extract complex match arms in lower_stmts_with_env into helper functions

[undivisible]

🎯 What: The lower_stmts_with_env function in in-cli/src/lower_core.rs was overly long (257 lines) and contained deeply nested, complex control flow logic for several AST statement types within a single massive match block. This PR extracts the logic for Stmt::If, Stmt::Loop, Stmt::Match, and Stmt::Try into dedicated, smaller helper functions.

💡 Why: A massive, monolithic function handling all statement lowering is difficult to read, maintain, and reason about. Extracting these complex branches into separate helper functions significantly reduces the cognitive load, isolates the specific lowering logic for each construct, and dramatically improves the maintainability of the lower_core module without altering any functionality.

✅ Verification: I successfully ran cargo fmt, cargo clippy, and the entire test suite (cargo test) locally to verify that no functionality was broken and no new warnings were introduced. I also verified the exact parameter passing and mutable borrows correctly mirror the original behavior.

✨ Result: The lower_stmts_with_env function is now much shorter, more readable, and easier to maintain. The complex lowering logic for conditionals, loops, matching, and try/catch blocks is cleanly compartmentalized into isolated helper functions.

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PR created automatically by Jules for task 8817524802857693550 started by @undivisible

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Note

Low Risk
Pure refactor of compiler lowering with logic moved verbatim into helpers; risk is limited to accidental behavior drift, which the existing tests are meant to catch.

Overview
Refactors statement lowering in lower_core.rs by pulling if, loop, match, and try handling out of the large lower_stmts_with_env match into dedicated helpers: lower_if_stmt, lower_loop_stmt, lower_match_stmt, and lower_try_stmt.

The main dispatcher now delegates to those functions and passes the same env, SSA counter, finish_with_return, and output buffer (with lower_try_stmt still honoring force_stores). Emitted SIL and control-flow structure are unchanged—this is a structural cleanup only.

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