feat: per-miner success rate in view rates and swap now

[anderdc]

What

Adds a Reliability column to alw view rates (the user-shopping table) and the alw swap now miner picker — per-miner, per-direction swap success rate, shown as completed/resolved and color-coded (green ≥90%, yellow ≥50%, red below).

Why

Today a user picks a miner by posted rate alone. A miner can quote the best rate and still fail most of its swaps, with no signal in the CLI to catch it before reserving. The column surfaces it — e.g. a miner showing T→B 1/17 has timed out 16 of its last 17 tao→btc swaps.

How

• fetch_miner_reliability() (helpers.py) aggregates resolved swaps (COMPLETED + TIMED_OUT — the same basis as the subnet's success_rate) from the public swap-history API.
• 30-day window, matching the subnet's credibility window.
• Cached 10 min, keyed by API host + window; paging stops once swaps predate the window.
• Degrades gracefully — returns None / renders — if the API is unreachable, so view rates and swap now still work offline of the indexer.
• ALLWAYS_API_URL env override.

Tests

tests/test_miner_reliability.py — aggregation, 30-day windowing, unresolved-status exclusion, API-unreachable, and a JSON-error-body guard.

Docs

Companion docs PR in allways-docs-ui updates cli.md.

Deferred (follow-ups)

• --sort reliability on view rates
• the same column on alw view miners
• making --auto reliability-aware