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/bxcore/src/lib.rs

@@ -0,0 +1,41 @@
+//! Shared data types and the frame codec for Boxmaker. No policy and no I/O beyond frames.
+
+pub mod audit;
+pub mod chain;
+pub mod class;
+pub mod escape;
+pub mod frame;
+pub mod gateway;
+pub mod grant;
+pub mod hash;
+pub mod hosts;
+pub mod ids;
+pub mod log;
+pub mod memory;
+pub mod sha1;
+pub mod tools;
+pub mod wire;
+
+pub use audit::{
+    ApprovalAnswer, AuditEvent, AuditRecord, DecisionRecord, ResultStatus, is_audit_log_name,
+};
+pub use chain::{ChainFailure, ChainReport, ChainVerifier, Location, TornTail};
+pub use class::DataClass;
+pub use frame::{FrameError, MAX_FRAME, read_frame, write_frame};
+pub use gateway::{
+    ApprovalOutcome, ApprovalPosted, ApprovalReply, ApprovalRequest, GatewayOutcome, MAX_REASON,
+    is_mattermost_id,
+};
+pub use grant::{Constraints, Grant, Mode};
+pub use hash::{HashError, Sha256, sha256};
+pub use ids::{CallId, Epoch, Hash32, SessionId, Timestamp, ValueError};
+pub use log::{LogRecord, ToolCall, Usage};
+pub use memory::{
+    ConsolidateEntry, EntryAction, MemoryAdmin, MemoryAdminReply, MemoryArgs, MemoryBlockReply,
+    MemoryCall, MemoryCommand, MemoryFile, RecallArgs, Reindexed, SessionUpdated,
+};
+pub use wire::{
+    ApprovalList, Approve, ApproveResult, DenyReason, Empty, Envelope, ErrorCode, GrantProblem,
+    GrantsReport, Message, PROTOCOL_VERSION, PendingApproval, Refuse, ToolRequest, ToolResponse,
+    Turn, TurnDone, TurnEvent, WireError,
+};