proto becomes bxcore, the one shared crate (M5b task 00)

Done the way the owner asked and the spike mapped: the crate and the
manifests renamed, then what the build reported fixed. Layers: 138
"proto unresolved" errors across 169 files; cargo fmt reordering
imports; six fixture paths built as strings in brokerd's and bxctl's
tests, which the compiler cannot see, and comments naming
crates/proto/; the crate-dependency check and its self-test. One more
the spike did not reach: a `\nproto =` key inside a printf format in
the self-test, which a word-boundary replacement skips because `n` and
`p` are both word characters.

make gate: gate: ok, 944 tests; no new entry in /tmp.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/gatewayd/src/approvals/mod.rs

@@ -7,7 +7,7 @@ use std::collections::{HashMap, HashSet};
 use std::sync::mpsc::Sender;
 use std::sync::{Mutex, MutexGuard};
 
-use proto::ApprovalReply;
+use bxcore::ApprovalReply;
 
 use crate::sessions::ApprovalCommand::{self, Approve, Deny, Malformed};
 

crates/gatewayd/src/approvals/text.rs

@@ -1,8 +1,8 @@
 //! The text of an approval's posts, and of the line added when it ends (M4b spec, section 6).
 //! Nothing here is shortened: arguments too long to show whole are not shown at all.
 
-use proto::escape::escape_json_text;
-use proto::{DenyReason, PendingApproval, Timestamp, sha256};
+use bxcore::escape::escape_json_text;
+use bxcore::{DenyReason, PendingApproval, Timestamp, sha256};
 
 /// Arguments are split into parts of at most this many characters.
 pub const PART_CHARS: usize = 15_000;
@@ -196,7 +196,7 @@ pub fn asked_post(id: u64, asked: &Asked) -> String {
     } else {
         "a direct message"
     };
-    let escaped = proto::escape::escape_model_text(&asked.prompt);
+    let escaped = bxcore::escape::escape_model_text(&asked.prompt);
     let total = escaped.chars().count();
     let shown: String = escaped.chars().take(PROMPT_SHOWN).collect();
     let mut post = format!(