`smallwebwaf rproxy` reads the first 64 KiB of each body, asks servewaf over
HTTP/1.1, and passes what servewaf allows to the app within its own limits. Any
other answer goes to the visitor as servewaf gave it. SWRP_DEFAULT_DISPOSITION
decides only when servewaf cannot be connected to, does not answer at all, or
does not answer within SWRP_TIMEOUT_MS. Only the methods SPEC.md lists pass on;
any other gets 405.
Duplication: internal/rproxy copies passing-on code from internal/proxy until
#172 removes the originals.
Rule suppressed: gosec G704 and G705; paralleltest on one test.
Judgement call: an answer over 1 MiB, or with a status below 100, gets 502.
Judgement call: every target not starting with one / gets 400.
Model: opus-5-5
