refactor: inline single-use is_write_method

[alukach]

What

is_write_method was a six-line matches! wrapper with exactly one caller. Inline it into the write-method short-circuit and delete the function.

if !is_special_path
    && matches!(
        parts.method,
        http::Method::PUT | http::Method::POST | http::Method::DELETE | http::Method::PATCH
    )
{

Why

One abstraction, one call site — the helper added a name but no reuse. The inlined matches! reads the same and removes the indirection.

Verification

Full pre-push suite (fmt, clippy wasm32, wasm check, tests) green.

Found via ponytail over-engineering audit.

🤖 Generated with Claude Code

[claude]

Claude finished @alukach's task in 21s —— View job

---

✅ No blocking issues — safe to merge.

• The dereference *method in the removed helper (which accepted &http::Method) is correctly dropped in the inlined form: parts.method is the owned value, so no deref is needed and matches! ergonomics handle it cleanly.
• Semantic equivalence is preserved — same four methods, same short-circuit position, same result.

[github-actions]

🚀 Latest commit deployed to https://source-data-proxy-pr-157.source-coop.workers.dev

• Date: 2026-06-18T23:35:55Z
• Commit: b27fe62