refactor(hooks): split config and executor modules

[cyq1017]

Problem

crates/tui/src/hooks.rs mixed hook config definitions with executor runtime behavior in one large module, which made hooks policy changes harder to review.

Change

• Move hook events, conditions, hook definitions, and HooksConfig into hooks/config.rs.
• Move HookExecutor, subprocess execution, timeout handling, stdout parsing, payload helpers, and tests into hooks/executor.rs.
• Keep the existing root crate::hooks::* API available through re-exports.

Closes #4082.

Verification

• cargo test -p codewhale-tui hooks:: --locked -- --nocapture
• RUSTFLAGS='-Dwarnings' cargo test -p codewhale-tui hooks:: --locked -- --nocapture
• cargo fmt --all -- --check
• git diff --check