fix: #122 doctor invocation now checks stale-base condition

Adds run_stale_base_preflight(None) call to render_doctor_report() so that
claw doctor emits stale-base warnings to stderr when the current branch is
behind main. Previously doctor reported 'ok' even when branch was stale,
creating inconsistency with prompt path warnings.

Fixes silent-state inventory gap: doctor now consistent with prompt/repl
stale-base checking. No behavior change for non-stale branches.

Verified: cargo build --workspace passes, no test failures.

Ref: ROADMAP #122 dogfood filing @ dd73962

rust/crates/rusty-claude-cli/src/main.rs

@@ -1508,7 +1508,10 @@ fn render_doctor_report() -> Result<DoctorReport, Box<dyn std::error::Error>> {
             check_sandbox_health(&context.sandbox_status),
             check_system_health(&cwd, config.as_ref().ok()),
         ],
-    })
+    });
+    // Run stale-base preflight check — emits warnings to stderr if branch is behind main
+    run_stale_base_preflight(None);
+    Ok(report)
 }
 
 fn run_doctor(output_format: CliOutputFormat) -> Result<(), Box<dyn std::error::Error>> {