docs: describe resil as a general-purpose library, not Bud's gateways

[dittops]

Summary

resil's docs described it as "traffic policy for Bud's gateways". They now describe what it does for any replicated service in front of upstreams:

• a local-first, Redis-synced rate and concurrency limiter
• failure classification, retry, circuit breaking and fallback chains

Changes

• Cargo.toml: generic description, plus keywords and categories.
• README and crate/module docs:
  • No references to budgateway, WaaV, budapp or budadmin, model_table / voice_table, or the bud-runtime spec's section numbers.
  • The benchmark baseline is now described as a "cached-counter" limiter design.
• Retry profiles renamed after what they are, not their first callers. Behaviour is unchanged.
  • Backoff::budgateway / RetryPolicy::budgateway → standard (1 s base, additive jitter)
  • Backoff::waav / RetryPolicy::waav → interactive (250 ms base, full jitter)
• Tests: comments no longer cite the Bud test-plan IDs; test names are generic.

Breaking: callers of the old profile names must rename. WaaV is the only caller, updated in its PR.

Dependents

The bud-runtime and WaaV PRs pin this branch's head 9be62f18ac968cb98e4ccc621c42cd73e960f9ba. Merge this PR with a merge commit, so that sha stays reachable from main. If it's squash- or rebase-merged instead, re-pin both.

Testing

cargo fmt --check
cargo clippy --all-targets --features redis-0-31 -- -D warnings
cargo clippy --all-targets --features redis-0-27 -- -D warnings
RUSTDOCFLAGS='-D warnings' cargo doc --no-deps --features redis-0-31
cargo +1.88.0 check --features redis-0-31                                           # MSRV
RESIL_TEST_REDIS_URL=redis://127.0.0.1:6390 cargo test --release --features redis-0-31

Results: 54 unit, 17 simulation, 4 Lua parity and 3 real-Valkey cluster tests pass.

🤖 Generated with Claude Code

[dittops]

Dependents pinning this branch's head (9be62f1): BudEcosystem/WaaV#10 and BudEcosystem/bud-runtime#3058. Merge this one first, with a merge commit.