keeper: rename sweep to run, ConditionalSource to Poller

[mfw78]

What

Renames videre-sdk::keeper::Sweep to Outcome, Keeper::sweep() to Keeper::run(), SweepReport to RunReport, and nexum-sdk::keeper::ConditionalSource<H> to Poller<H>. Removes the word sweep from keeper docs, comments, and test file names (composable-cow/tests/sweep.rs to run.rs, composable-cow/src/sweep.rs to run.rs).

Why

The 2026-07-14 keeper vocabulary freeze rejected sweep and kept Verdict, but the L2 keeper introduced in #454 re-shipped Sweep/.sweep()/SweepReport. Sweep also named the enum after the loop that consumes it rather than the per-watch poll outcome it represents, and ConditionalSource read as a stream producer when it evaluates one watch and returns one outcome. This must land before the M5 three-repo split, after which nexum-sdk and videre-sdk live in separate repos and the rename becomes a coordinated two-repo change.

Testing

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets --all-features --locked -- -D warnings
• cargo build --release --target wasm32-wasip2 --locked (16 modules)
• cargo build --release --target wasm32-wasip2 --locked -p cow-venue --features cow-venue/adapter
• wasm count verified at 17
• cargo nextest run --workspace --all-features --no-fail-fast --locked
• cargo test --doc --workspace --all-features --locked
• RUSTDOCFLAGS="-D warnings" cargo doc --workspace --no-deps --locked
• ./scripts/check-venue-agnostic.sh
• ./scripts/check-cow-orderbook-only.sh

AI Assistance

Implemented with Claude Code.

Closes #540