fix(peer-files): stream large cloud downloads + surface real errors (#30, #38)

Large peer downloads (~178MB) failed with a generic 'Operation failed', and
the download path had three stacked problems:

- The FIPS reqwest client used a hard-coded 20s total timeout regardless of the
  caller's .timeout(), so a big transfer over the mesh aborted at 20s before
  the Tor fallback could help. Honor the per-request timeout (client_with_timeout).
- The peer-content proxy buffered the whole file into node memory via
  resp.bytes() before sending a byte, and capped the transfer at 60s. Stream
  the body through with hyper::Body::wrap_stream (constant memory) and raise the
  timeout to 900s; bump the nginx peer-content read timeout to match.
- Free downloads pulled the file as base64 over RPC, doubling it in node memory
  and the browser — fatal for large files. Download free files by streaming
  from /api/peer-content straight to disk, after a 1-byte Range probe that
  surfaces the real reason (peer offline on mesh and Tor) instead of a generic
  failure. Paid downloads now return the real error through the {error} channel
  the UI already displays.

Adds the reqwest 'stream' feature for bytes_stream().

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

core/archipelago/Cargo.toml

@@ -64,7 +64,7 @@ serde_yaml = "0.9"
 
 # HTTP client (for LND REST proxy, Tor SOCKS for peer messaging)
 # Uses rustls-tls for cross-compilation (no OpenSSL dependency)
-reqwest = { version = "0.11", default-features = false, features = ["json", "socks", "rustls-tls"] }
+reqwest = { version = "0.11", default-features = false, features = ["json", "socks", "rustls-tls", "stream"] }
 
 # Nostr (node discovery + NIP-44 encrypted peer handshake)
 nostr-sdk = { version = "0.44", features = ["nip04", "nip44"] }