docs(compression): minBodyBytes default mismatch — doc says 1 KB, code uses 512

[momics]

Summary

docs/features/compression.md documents compression.minBodyBytes as default 1 KB, but the actual default in the Rust core is 512 bytes (crates/iroh-http-core/src/config.rs — min_body_bytes: usize with Default: 512). Fix the doc to match the code (or change the code if 1 KB is intended).

Evidence

• Doc (docs/features/compression.md line 19): minBodyBytes: 1024, // skip compression below this size (default 1 KB)
• Code (crates/iroh-http-core/src/config.rs): default constant is 512.
• The Node FFI bridge (packages/iroh-http-node/src/lib.rs line 420) also defaults to 512 when compressionMinBodyBytes is None.

Impact

Cosmetic: developers tuning compression behaviour read the doc, expect compression to skip bodies below 1 KB, and instead see compression on bodies between 512 B and 1 KB.

Remediation

Two options — pick one:

1. Fix the doc to say default 512 bytes (lowest-friction).
2. Change the default to 1 KB in config.rs and the Node bridge (matches the convention used by most HTTP servers; the tower-http SizeAbove predicate's built-in default is 32 but most servers tune higher).

Acceptance criteria

• Documented default and code default agree.
• A CompressionOptions::default() test asserts the value (regression guard).