docs: consolidate all docs under docs/ — single source of truth

Move issues (01–29) and PRD from .scratch/distributed-inference-network/
into docs/issues/ and docs/. Update ralph_progress.py DEFAULT_PRD path
and rewrite docs/agents/issue-tracker.md to reflect the new layout.

The distributed_inference_network.egg-info/docs/ mirror is a build
artifact already covered by *.egg-info/ in .gitignore — not committed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/issues/29-relay-outbound-client.md

@@ -0,0 +1,44 @@
+# US-029 — Outbound relay client: NAT/internet pipeline hops
+
+Status: done
+Priority: Critical
+Stage: Implemented
+
+## Context
+
+Nodes behind NAT (WSL2 with 172.x.x.x addresses, 5G mobile, home routers) register with the
+tracker and include a `relay_addr` (`wss://relay/rpc/{peer_id}`). When the head node needs to
+forward activations to such a peer, it currently fails because the direct HTTP endpoint is
+unreachable.
+
+The relay server (US-017) is already running and the node already opens a persistent outbound
+WebSocket (`RelayHttpBridge`). What is missing is the *outbound caller side*: given a `relay_addr`,
+open a per-hop WebSocket to the relay's `/rpc/{peer_id}` endpoint and send the activation through it.
+
+## Protocol
+
+```
+Node A  →  WS connect wss://relay/rpc/{peer_id_B}
+       →  send JSON: {request_id, method, path, headers, body_base64}
+Relay   →  forward as relay-http-request envelope to Node B's persistent WS
+Node B  →  process /forward locally
+       →  send relay-http-response envelope back
+Relay   →  resolve future, send response JSON to Node A
+Node A  ←  {request_id, status, headers, body_base64}
+```
+
+Binary activations (bfloat16) are base64-encoded. No precision loss.
+
+## Acceptance criteria
+
+- [ ] `_relay_hop(relay_addr, path, body, headers, timeout)` in `torch_server.py` — opens WS, sends, receives, returns `(status, headers_lower, body_bytes)`
+- [ ] `_get_remaining_route` returns `list[dict]` with `relay_addr` field (was `list[tuple]`)
+- [ ] `_run_downstream_pipeline` dispatches via `_relay_hop` when hop has `relay_addr`; falls back to direct HTTP if relay connection fails
+- [ ] Tracker `_handle_proxy_chat` includes `relay_addr` in downstream hop dicts when node has one
+- [ ] `relay_bridge._handle_request` decodes `body_base64`; response uses `body_base64` for `octet-stream` content
+- [ ] All 157 tests pass (`python -m pytest`)
+- [ ] QUICKSTART.md updated with relay NAT/internet architecture and test scenario
+
+## WSL2 test scenario
+
+Start two nodes in WSL2 pointing at the public tracker. Both get `172.x.x.x` endpoints (unreachable from outside). Both connect to relay automatically. Send an inference request through the tracker — activations flow via relay. No `--advertise-host` needed.