Agent support for CodeWhale

[Mr-Moon121]

idea / problem

CodeWhale (github.com/Hmbown/CodeWhale) is a terminal coding agent — DeepSeek-first, Rust TUI, ratatui-based. Currently not detected by herdr. It has clear, stable visual markers across all three states, similar in simplicity to pi.

requested change

Add CodeWhale to detected agents with screen heuristics:

• Working: braille spinner line ⠋ Working… ( 13m 36s · esc to interrupt) — always present while active
• Blocked: permission UI Do you want to proceed? + numbered choices + esc to cancel
• Idle: prompt line ending with ❯, guarded against working/blocked patterns with not clauses

why you want this

CodeWhale runs entirely in the terminal with a consistent UI. The three detection markers are unambiguous and stable. A validated manifest exists — tested against real screen captures with herdr agent explain --file, all three states detect correctly. PR scope is small: +1 enum variant, +1 process mapping, +1 TOML manifest (~50 lines total). No integration hook needed for initial support (screen manifest only).

[atmosuwiryo]

Implemented — details in #2420

This request matches completed work: a contributed herdr branch adding
codewhale detection (idle / working / blocked) via a screen + OSC manifest.

Status: on a branch in my fork, proposed upstream — not merged or shipped
yet.

Branch feat/codewhale-agent (commit 97d1c9f9) at
https://github.com/atmosuwiryo/herdr

Covers all three states (spinner strip → working, approval band → blocked,
❯ composer → idle) plus OSC title/progress signals, sound overrides, and
docs. Verified with herdr agent explain --file against real captures and
99 passing detect:: tests (5 new codewhale tests).

Full write-up with evidence: #2420