Resolve off-chain swaps via Allways DAS indexer

[eureka0928]

Summary

When a swap completes or times out, the contract removes it from on-chain storage. Currently alw view swap <id> shows a generic "Swap resolved" message with no details — users lose visibility into their swap history.

This PR adds a lightweight fallback to the existing Allways DAS (indexer) API so resolved swaps are displayed with full details instead of a dead-end message.

• No new infrastructure — uses the already-deployed indexer at test-api.all-ways.io
• Best-effort only — if the indexer is unreachable or returns bad data, the existing "resolved" message is shown as before
• Zero impact on happy path — DAS is only called when get_swap() returns None

Changes

Commit 1: Resolve off-chain swaps via Allways DAS indexer

• New allways/cli/das_api.py — thin client for GET /swaps/{id}, maps indexer JSON to the existing Swap dataclass
  • TAO decimal string → rao conversion (_tao_decimal_to_rao)
  • Validates chains against SUPPORTED_CHAINS
  • Configurable base URL via ALLWAYS_DAS_BASE_URL env var
  • Returns None on any transport/parse error (never raises)
• Modified allways/cli/swap_commands/view.py — when get_swap() returns None, tries fetch_swap_from_das() before falling back to the old message
• Tests: full coverage of field mapping, fallback ID, bad payloads, network errors, unsupported chains, unparseable integers

Commit 2: Clarify SwapTracker docs and add unit tests

• Expanded SwapTracker docstring explaining window pruning, voted_ids lifecycle, and cold-start behavior
• Tests: _resolved_block ordering, window pruning, voted_ids cleanup on swap resolution

Example

Before:

$ alw view swap 1
Swap 1 has been resolved (completed or timed out).
Resolved swaps are removed from on-chain storage.

After:

$ alw view swap 1
Swap no longer on-chain; showing indexer record.

Swap #1 — COMPLETED

  BTC -> TAO | 0.005 BTC -> 1.72650000 TAO | Rate: 345.3

  Timeline:
    ● Initiated      Block 8000
    ● Fulfilled       Block 8050
    ● Completed       Block 8120
    ⏱ Timeout        Block 9000

  Source TX: abc123...
  Dest TX:   def456...

  User:    5GrwvaEF...
  Miner:   5FHneW46...

Test plan

• pytest tests/test_das_api.py -v — DAS client mapping and error handling
• pytest tests/test_swap_tracker.py -v — SwapTracker pruning and voted_ids cleanup
• Manual: alw view swap <resolved_id> shows full details from indexer
• Manual: with ALLWAYS_DAS_BASE_URL set to invalid URL, falls back to existing message

[eureka0928]

Hi @LandynDev I put the new PR based on your comments from closed one
Thank you for your time
Let me know if there is any feedback