report: grow the Prompter port and move display_path out of the ui module

Prompter gains interactive(), select() and text() (with the Validator
type), and confirm() now propagates cancellation as Err so flows abort
instead of silently taking a default when the user hits Ctrl+C. The
terminal prompter implements the full port; the port also re-exports
the path display helper, which is pure presentation formatting used by
events and messages rather than terminal code.

src/ui/deb.rs

@@ -232,7 +232,7 @@ impl DebUi {
         if self.shared.enabled && !artifacts.is_empty() {
             println!("Built in {}s:", elapsed.as_secs());
             for artifact in artifacts {
-                println!("  {}", crate::ui::display_path(artifact));
+                println!("  {}", crate::report::display_path(artifact));
             }
         }
     }

src/ui/prompt.rs

@@ -12,7 +12,7 @@ use crossterm::{
     style::{self, Color, Print, SetForegroundColor},
     terminal,
 };
-use std::io::{self, Write};
+use std::io::{self, IsTerminal, Write};
 use std::time::Duration;
 
 /// Why a prompt could not run interactively
@@ -32,9 +32,8 @@ impl std::fmt::Display for PromptError {
 
 impl std::error::Error for PromptError {}
 
-/// Answer validator of [`text`]: accepts the answer, or explains why it is
-/// rejected
-pub type Validator = dyn Fn(&str) -> Result<(), String>;
+/// Answer validator of [`text`] (re-exported from [`crate::report`])
+pub use crate::report::Validator;
 
 /// What a prompt's event loop asks its drawing helper to render; keeping all
 /// terminal access behind this callback makes the loops pure logic that unit
@@ -128,13 +127,37 @@ pub fn confirm(label: &str, default: bool) -> Result<bool, Box<dyn std::error::E
 }
 
 /// [`crate::report::Prompter`] answered by the interactive terminal: each
-/// question runs the matching raw-mode prompt, falling back to the default
-/// answer when no interactive terminal is attached (CI, piped input).
+/// question runs the matching raw-mode prompt. Without an interactive
+/// terminal (CI, piped input) [`Prompter::interactive`] is false — flows
+/// then take their headless path instead of asking — and a cancel (Ctrl+C)
+/// propagates as `Err` so flows can abort.
 pub struct TerminalPrompter;
 
 impl crate::report::Prompter for TerminalPrompter {
-    fn confirm(&self, question: &str, default: bool) -> bool {
-        confirm(question, default).unwrap_or(default)
+    fn interactive(&self) -> bool {
+        std::io::stdin().is_terminal() && std::io::stdout().is_terminal()
+    }
+
+    fn confirm(&self, question: &str, default: bool) -> Result<bool, Box<dyn std::error::Error>> {
+        confirm(question, default)
+    }
+
+    fn select(
+        &self,
+        label: &str,
+        options: &[String],
+        default: &str,
+    ) -> Result<String, Box<dyn std::error::Error>> {
+        select(label, options, default)
+    }
+
+    fn text(
+        &self,
+        label: &str,
+        default: &str,
+        validate: Option<&Validator>,
+    ) -> Result<String, Box<dyn std::error::Error>> {
+        text(label, default, validate)
     }
 }