feat(executor): expose ctx.request.method to scripts (F4)

The request map exposed path/headers/body/params/query/rest but not the
HTTP method, forcing one script per verb (the E2E app needed 7 scripts
where ~3 would do). Add a `method` field to ExecRequest (populated from
the HTTP method on the sync-execute bypass and the HTTP outbox payload;
empty for non-HTTP triggers) and surface it as `ctx.request.method`,
uppercased. A single script can now branch GET/POST on one route.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/executor-core/src/engine.rs

@@ -485,6 +485,7 @@ fn build_ctx_map(req: &ExecRequest) -> Map {
 
     let mut request = Map::new();
     request.insert("path".into(), req.path.clone().into());
+    request.insert("method".into(), req.method.clone().into());
 
     let mut headers = Map::new();
     for (k, v) in &req.headers {