feat(alpha): complete hardening backlog

Complete the alpha-hardening Ralph task set, including tracker billing/accounting guards, validator fraud-audit primitives, wallet binding proof support, documentation runbooks, and updated tests.

Verification: .venv/bin/python -m compileall -q packages tests; .venv/bin/python -m pytest -q --tb=short (313 passed, 3 skipped, 1 failed: tests/test_mining_cli.py::test_legacy_start_without_port_uses_next_available_port because meshnet-node pid 1263451 is already listening on port 7000).

packages/tracker/pyproject.toml

@@ -9,6 +9,7 @@ description = "Distributed Inference Network node registry and route selection"
 requires-python = ">=3.10"
 
 dependencies = [
+    "cryptography>=41",
     "websockets>=13",
 ]