proto: escape, moved from bxctl so gatewayd shows the same thing

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/bxctl/src/escape.rs

@@ -1,43 +1,3 @@
-//! The two text-escape helpers the owner's client needs.
+//! The text-escape helpers, from `proto` (moved there in M4b so `gatewayd` shows the same thing).
 
-// The control bytes, the zero-width and Unicode line/paragraph separators, and the BOM. A code
-// point in any of these ranges must never reach the terminal raw.
-const ESCAPE_RANGES: &[(u32, u32)] = &[
-    (0x0000, 0x001f),
-    (0x007f, 0x009f),
-    (0x200b, 0x200f),
-    (0x2028, 0x202e),
-    (0x2060, 0x2069),
-    (0xfeff, 0xfeff),
-];
-
-pub fn escape_json_text(s: &str) -> String {
-    escape(s, false)
-}
-
-pub fn escape_model_text(s: &str) -> String {
-    escape(s, true)
-}
-
-fn escape(s: &str, model_text: bool) -> String {
-    let mut out = String::with_capacity(s.len());
-    for c in s.chars() {
-        let cp = u32::from(c);
-        if should_escape(c, model_text) {
-            out.push_str(&format!("\\u{:04x}", cp));
-        } else {
-            out.push(c);
-        }
-    }
-    out
-}
-
-// A control point is escaped, except that model text keeps \n and \t.
-fn should_escape(c: char, model_text: bool) -> bool {
-    let cp = u32::from(c);
-    if ESCAPE_RANGES.iter().any(|(lo, hi)| cp >= *lo && cp <= *hi) {
-        !(model_text && (cp == 0x09 || cp == 0x0a))
-    } else {
-        false
-    }
-}
+pub use proto::escape::{escape_json_text, escape_model_text};