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).

.scratch/alpha-hardening/runbooks/01-ledger-backup.md

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+Status: stub
+
+# Runbook: Ledger backup
+
+Covers backing up the tracker's authoritative money/trust state — the billing
+ledger, dashboard accounts DB, and node registry (strike/ban/reputation) — and
+how to pause hive gossip during the backup window so peers don't replicate
+against a half-copied file.
+
+## Trust assumptions (read first)
+
+Per [ADR-0016](../../../docs/adr/0016-alpha-scope-and-known-limitations.md), one
+operator-designated tracker holds the treasury keypair and is the source of
+truth for settlement; other hive members only replicate. Back up **that**
+tracker's databases — a follower's copies are eventually consistent, not
+authoritative. See [ADR-0015](../../../docs/adr/0015-usdt-custodial-settlement.md)
+for the settlement loop these tables feed.
+
+## Prerequisites
+
+- Shell access to the settlement-capable tracker host.
+- `sqlite3` CLI (or `.backup` support in the Python `sqlite3` module) available
+  for online, consistent snapshots.
+- Know the tracker's configured DB paths — defaults, unless overridden by CLI
+  flags:
+  - Billing ledger: `billing.sqlite` (`--billing-db`, `DEFAULT_BILLING_DB_PATH`
+    in `packages/tracker/meshnet_tracker/billing.py`)
+  - Dashboard accounts: `accounts.sqlite` (`--accounts-db`,
+    `DEFAULT_ACCOUNTS_DB_PATH` in `packages/tracker/meshnet_tracker/accounts.py`)
+  - Node registry (strike/ban/reputation event log,
+    `packages/contracts/meshnet_contracts/__init__.py::RegistryEventLog`): path
+    is whatever was passed as `registry_db` when the tracker's
+    `LocalSolanaContracts` was constructed. **As of this writing the tracker
+    CLI (`meshnet_tracker/cli.py`) does not expose a `--registry-db` flag or
+    wire a `contracts=` instance into `TrackerServer` by default** — confirm
+    with whoever deployed this tracker whether registry persistence is
+    actually enabled before assuming a file exists to back up. If it isn't
+    wired up yet, strike/ban/reputation state is RAM-only and this step is
+    moot until that gap closes (tracked loosely against issue 05).
+
+## Steps
+
+1. Identify the actual DB paths in use (check the tracker's start command /
+   systemd unit / process env for `--billing-db`, `--accounts-db`, and any
+   registry DB argument).
+2. **Pause hive gossip** on this tracker so peers don't pull a partial/locked
+   file mid-backup:
+   - If the tracker is the sole settlement node with no `--cluster-peers`,
+     gossip is already off — skip to step 3.
+   - Otherwise, stop replication by restarting the process without
+     `--cluster-peers` (or with an empty peer list) for the duration of the
+     backup, or take the backup during a maintenance window with peers
+     temporarily pointed away from this tracker at the load balancer/DNS
+     level. There is currently no live "pause gossip" admin endpoint — this is
+     a process-restart-level operation.
+   - Confirm no in-flight `/v1/registry/gossip`, `/v1/billing/gossip`, or
+     `/v1/accounts/gossip` traffic before proceeding (check access logs).
+3. Take an online, consistent copy of each SQLite file using the backup API
+   rather than `cp` (WAL-mode files can be mid-write):
+   ```
+   sqlite3 billing.sqlite ".backup '/backups/billing-$(date +%Y%m%dT%H%M%S).sqlite'"
+   sqlite3 accounts.sqlite ".backup '/backups/accounts-$(date +%Y%m%dT%H%M%S).sqlite'"
+   # registry DB, if configured:
+   sqlite3 registry.sqlite ".backup '/backups/registry-$(date +%Y%m%dT%H%M%S).sqlite'"
+   ```
+4. Verify each backup opens and has rows in its expected tables
+   (`billing_ledger`/event log tables, `accounts`, `registry_events`).
+5. Resume gossip (restore `--cluster-peers` / routing) once backups are
+   confirmed good.
+6. Ship backups off-host per your normal retention policy. Do not store them
+   alongside `.env.devnet` or keypair files (see secrets handling below).
+
+## Rollback
+
+- If a restore is needed, stop the tracker, replace the live `.sqlite` file(s)
+  with the chosen backup, and restart. Because billing/accounts/registry each
+  use append-only event logs, a stale restore under-counts recent activity
+  rather than corrupting state — reconcile any gap against node/operator
+  reports for the missing window before resuming payouts.
+- If gossip was paused via a peer-list restart, confirm peers re-sync
+  (`events_since` catch-up) before considering the rollback complete.
+
+## Secrets handling
+
+- Never commit `.env.devnet`, treasury keypair JSON files, `--hive-secret`, or
+  `--validator-service-token` values to a repo or ship them inside a DB backup
+  archive. Back these up separately, encrypted, per your existing secrets
+  process.