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/loopd/src/llama/assemble.rs

@@ -201,7 +201,7 @@ impl Assembler {
                     ));
                 }
             };
-            tool_calls.push(proto::ToolCall {
+            tool_calls.push(bxcore::ToolCall {
                 id,
                 name,
                 arguments: call.arguments,

crates/loopd/src/llama/mod.rs

@@ -18,7 +18,7 @@ pub enum ChatMessage {
     Assistant {
         content: Option<String>,
         reasoning_content: Option<String>,
-        tool_calls: Vec<proto::ToolCall>,
+        tool_calls: Vec<bxcore::ToolCall>,
     },
     Tool {
         tool_call_id: String,
@@ -93,7 +93,7 @@ pub struct Completion {
     pub id: String,
     pub content: Option<String>,
     pub reasoning_content: Option<String>,
-    pub tool_calls: Vec<proto::ToolCall>,
+    pub tool_calls: Vec<bxcore::ToolCall>,
     pub finish_reason: FinishReason,
     pub timings: Timings,
     pub reasoning_tokens: u64,

crates/loopd/src/llama/request.rs

@@ -73,7 +73,7 @@ fn serialize_message(message: &ChatMessage) -> Result<serde_json::Value, serde_j
     }
 }
 
-fn serialized_call(call: &proto::ToolCall) -> SerializedToolCall {
+fn serialized_call(call: &bxcore::ToolCall) -> SerializedToolCall {
     SerializedToolCall {
         id: call.id.clone(),
         kind: "function",