test(qa-pty): retarget harness at codewhale-tui binary

The qa_pty integration tests booted the canonical TUI via
`Harness::cargo_bin("deepseek-tui")`. After the previous commit
renamed the canonical bin to `codewhale-tui` and made `deepseek-tui`
a tiny deprecation shim that forwards to it via PATH, those tests
launched the shim and hung waiting for a TUI frame because the
sealed PATH in the test sandbox has no `codewhale-tui`.

Point the harness at `cargo_bin("codewhale-tui")` directly. Also
add a `CARGO_BIN_EXE_codewhale-tui` compile-time fallback in the
harness so older Cargo versions still work, alongside the existing
legacy `deepseek-tui` fallback.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/tui/tests/qa_pty.rs

@@ -38,7 +38,7 @@ fn boot_minimal_without_retry() -> anyhow::Result<(qa_harness::harness::SealedWo
 fn spawn_minimal(
     ws: qa_harness::harness::SealedWorkspace,
 ) -> anyhow::Result<(qa_harness::harness::SealedWorkspace, Harness)> {
-    let h = Harness::builder(Harness::cargo_bin("deepseek-tui"))
+    let h = Harness::builder(Harness::cargo_bin("codewhale-tui"))
         .cwd(ws.workspace())
         .seal_home(ws.home())
         // Provide a stub key so the onboarding screen is bypassed and the TUI
@@ -165,7 +165,7 @@ fn skills_menu_shows_local_and_global_skills() -> anyhow::Result<()> {
         "Workspace beta skill",
     )?;
 
-    let mut h = Harness::builder(Harness::cargo_bin("deepseek-tui"))
+    let mut h = Harness::builder(Harness::cargo_bin("codewhale-tui"))
         .cwd(ws.workspace())
         .seal_home(ws.home())
         .env("DEEPSEEK_API_KEY", "ci-test-key-not-real")

crates/tui/tests/support/qa_harness/README.md

@@ -46,7 +46,7 @@ spin up a PTY just to assert a function returns the right value.
 3. Spawn:
 
    ```rust
-   let mut h = Harness::builder(Harness::cargo_bin("deepseek-tui"))
+   let mut h = Harness::builder(Harness::cargo_bin("codewhale-tui"))
        .cwd(ws.workspace())
        .seal_home(ws.home())
        .env("DEEPSEEK_API_KEY", "ci-test-key")

crates/tui/tests/support/qa_harness/harness.rs

@@ -221,6 +221,12 @@ impl Harness {
         if let Some(path) = std::env::var_os(&key) {
             return PathBuf::from(path);
         }
+        if name == "codewhale-tui"
+            && let Some(path) = option_env!("CARGO_BIN_EXE_codewhale-tui")
+        {
+            return PathBuf::from(path);
+        }
+        // Legacy fallback for callers still referencing the old bin name.
         if name == "deepseek-tui"
             && let Some(path) = option_env!("CARGO_BIN_EXE_deepseek-tui")
         {