feat: add economically optimized Loop Out CLI tool with real route probing and SOT accounting

[TrezorHannes]

Summary of Changes

1. Economic Loop Out CLI Optimizer (Other/swap_out-loop.py):

   • Discovers channel candidates with high local liquidity and low outbound fees via LNDg API.
   • Dynamic per-channel equilibrium sizing (targeting 50% balance) or explicit --amt <sats>.
   • Two-stage route validation:
     • Stage 1: lncli queryroutes Dijkstra pathfinding to Loop node (021c97a9...).
     • Stage 2: Mandatory live prepay probe with random 32-byte fake hashes via lncli sendpayment to detect ghost liquidity and verify real downstream routing paths.
     • Direct 2-Hop Probing Fallback: Checks if peer maintains a direct channel to Loop, building route via lncli buildroute and probing via lncli sendtoroute to accurately determine real routing fees.
   • Comprehensive total economic cost calculation:
     29383\text{Total Cost} = \text{Loop Service Fee} + \text{On-chain Sweep Fee} + \text{LN Routing Fee} + \text{Opportunity Cost (PPM)}29383
   • Ranking candidates by lowest Net Effective PPM.
   • Interactive terminal menu navigation (↑/↓/Enter/q) using native termios/tty, with clean PrettyTable fallback for non-TTY pipelines and --auto-approve.
   • Concurrent worker probing via --workers <N> (using ThreadPoolExecutor with thread-safe output) while preserving 15s probe timeout.
   • Economical on-chain sweeping: enforces minimum 6-block confirmation target (default 9) and omits --fast for fee-saving swap batching.

2. Native Source of Truth (SOT) Accounting via Loop's loop.db:

   • Directly connects in read-only mode to Loop daemon's SQLite database (~/.loop/mainnet/loop_sqlite.db), eliminating redundant custom databases and state divergence.
   • Configurable via loop_db_path in config.ini, with seamless RPC fallback to litloop listswaps.
   • Automatically tags initiated swaps with --label "Loop-Out: <alias> (<chan_id>)" to preserve channel metadata natively in loop.db.
   • Historical querying CLI: python Other/swap_out-loop.py --history [--limit N] displaying actual settled costs and realized PPM.
   • On-demand CSV export: --history --csv [path].

3. Documentation & Config:

   • Comprehensive documentation in Other/swap_out-loop.md.
   • Documented [loop] section in config.ini.example and live Debian NUC config.ini.
   • Updated README.md tool index.

4. Testing & Live Verification:

   • 17 unit tests in tests/Other/test_swap_out_loop.py covering candidate filtering, dynamic sizing, quote parsing, economic scoring, route probing, direct route fallback, SOT SQLite querying, and CSV export.
   • Entire test suite passing: 91/91 tests pass.
   • Verified live on debian-nuc.lan with live --dry-run, --workers 2, --history, and real on-chain execution.

Verification

• Automated Tests: pytest passed 91/91 tests in 15.6s.
• Debian NUC Live Testing: Verified live on debian-nuc.lan with dry-run, workers, history, and real swap execution.