Review M1: accept with two follow-up tasks

The branch passes the checklist: seven commits, copied files unchanged,
gate and audit green. Reading and probing found that AuditRecord and
ToolCall accept unknown fields, that large Timestamps panic when
formatted, and that the dependency-direction scripts miss table-form
dependencies and pass when their inputs are missing. The last two
families were gaps in the tasks, not only in the code.

Tasks 08 and 09 carry the fixes, defined by an exhaustive unknown-field
test, a bounded-Timestamp test and an extended gate-script self-test.
All three were checked against the reference implementation and fail on
the current branch.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

AGENTS.md

@@ -42,7 +42,8 @@ Unix sockets. You are implementing it one task at a time.
 ## The gate
 
 `make gate` must print `gate: ok` before a task is done. It runs offline: rustfmt, clippy with
-warnings denied, all tests, cargo-deny, and the scripts in `scripts/`. After you add a dependency,
+warnings denied, all tests, cargo-deny, and the scripts in `scripts/`. Run `cargo fmt --all` before
+the gate; rustfmt decides the order of `mod` and `use` lines, not you. After you add a dependency,
 run `cargo build` once so that `Cargo.lock` is updated, then run the gate.
 
 Useful while working: `cargo test -p <crate> --test <file>` runs one test file, and