Parser: block-like expressions as statements without trailing `;`

[StreamDemon]

Summary

block_inner treats any non-semicolon-terminated expression as the block tail and stops, so a block-like expression used in statement position (if … {}, match … {}, { … }, loops) must currently be the tail or carry an explicit trailing ;. A statement-position block expression followed by more statements fails to parse (e.g. if c { a(); } more();).

Surfaced during PR #57 verification; documented in crates/AGENTS.md.

Spec

• §5: block-like expressions (if, match, loops, blocks) used in statement position do not require a trailing ; (Rust precedent). §16 statement vs. expression-statement grammar.

Scope

• In block_inner, recognize block-like expressions (if/match/while/for/loop/{}) in statement position and continue parsing subsequent statements without requiring ;.
• Preserve existing tail-expression behavior for value-producing tails.
• Corpus fixture: a function body with an if-statement followed by further statements.
• Unit tests for statement-position if (extend to match/loops as they land).

Notes

Cleanest after match and the loop constructs land, so the "is this block-like?" check covers them in one place. Can land for if only first, then extend.