fix(hook): rewrite wc commands to rtk wc

[manulqwerty]

Summary

• rewrite wc commands through the hook by removing "wc " from IGNORED_PREFIXES
• add wc to the discover/rewrite registry so wc ... becomes rtk wc ...
• cover the regression with classification and rewrite tests, and document it in the changelog

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test
• Manual testing: rtk <command> output inspected
• cargo fmt --all --check
• cargo test test_classify_wc_supported -- --nocapture
• cargo test test_rewrite_wc -- --nocapture
• Manual hook test (Copilot VS Code payload): wc -l src/main.rs rewrites to rtk wc -l src/main.rs
• Manual hook test (Gemini payload): wc -l src/main.rs rewrites to rtk wc -l src/main.rs
• Manual output check: wc -l src/main.rs -> 2643 src/main.rs, rtk wc -l src/main.rs -> 2643

Clippy currently fails on pre-existing unrelated warnings in src/gh_cmd.rs and src/git.rs on this branch baseline, so the full cargo fmt --all && cargo clippy --all-targets && cargo test box is left unchecked.

[CLAassistant]

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