Revise HTTPS Outcalls skill documentation

[fspreiss]

Updates the HTTP Outcall skill documentation as follows:

• Fix Motoko example to compile and run correctly. Replace hand-rolled type definitions with the compiler-provided import IC "ic:aaaaa-aa" types, add the missing is_replicated field, and use Blob directly instead of [Nat8] for the response body.

• Fix consensus failures in POST examples. Add a dedicated transformPost function (both Motoko and Rust) that strips the response body in addition to headers, because httpbin.org's /post endpoint returns the caller's IP in the origin field, which differs across replicas. POST functions now return a status message instead of the non-deterministic body.

• Use automatic cycle attachment. Replace hardcoded cycle amounts with Call.httpRequest from the ic mops package (Motoko) and document that ic_cdk::management_canister::http_request (Rust) does the same. Both use the ic0.cost_http_request system API under the hood.

• Add pitfall for omitting max_response_bytes. New pitfall Improve repo structure, CI pipeline, and contributor experience #5 warns that omitting it defaults to 2MB and charges ~21.5B cycles on a 13-node subnet.

• Correct the cycle cost formula. The original formula had request_bytes and response_bytes swapped. Updated with the correct per-byte rates (5,200/request byte, 10,400/max_response_bytes byte on a 13-node subnet), explained that the charge is against max_response_bytes (not actual response size), and documented the ic0.cost_http_request system API for runtime cost calculation.

• Update prerequisites to require moc >= 0.14.10 and ic >= 2.1.0 in mops.toml.

[derlerd-dfinity]

Nice! Thanks a lot!