nx_mgmt_upload.nx

nx_mgmt_upload.nx -- CAP-API-UPLOAD: the #1 census gap = binary UPLOAD over /api, the "not-on-LAN deploy" unblocker. The mgmt accept loop reads one request into a fixed SD_REQCAP(64KB) buffer, so a multi-MB binary cannot ride a single POST. Answer: CHUNKED staging -- the client sends ordered ~48KB `POST /api/upload?target=..&seq=N` chunks; this primitive assembles them into the allowlisted staging file (seq 0 = fresh/truncate, seq>0 = append), then /api/deploy promotes + the self-safe marker (nx_deploy_marker) restarts. Deterministic + resumable-by-seq. SECURITY: `path` MUST be pre-resolved through the deploy allowlist (md_resolve_target) by the caller -- this is the write primitive only, single-responsibility. license_tier: ORIGINAL