fix: force AI agents to execute commands from the root of the repo (#9174)

Even despite the instruction to execute the specified commands in
`.claude/CLAUDE.md` from the root of the repository, agents would often
ignore it and execute the commands from some subdirectory causing them
to misbehave. To fix this we explicitly prefix each command with `cd
"$(git rev-parse --show-toplevel)"`.

Author: basvandijk

.claude/CLAUDE.md

@@ -8,11 +8,13 @@ After changing Rust code (`*.rs`) follow these steps in order:
 
 1. **Format** by running the following from the root of the repository:
    ```
+   cd "$(git rev-parse --show-toplevel)"
    rustfmt <MODIFIED_RUST_FILES>
    ```
    where `<MODIFIED_RUST_FILES>` is a space separated list of paths of all modified Rust files relative to the root of the repository.
 2. **Lint** by running the following from the root of the repository:
    ```
+   cd "$(git rev-parse --show-toplevel)"
    cargo clippy --all-features <CRATES> -- \
        -D warnings \
        -D clippy::all \
@@ -30,6 +32,7 @@ After changing Rust code (`*.rs`) follow these steps in order:
    Fix any linting errors.
 3. **Build** the directly affected bazel targets by running the following from the root of the repository:
    ```
+   cd "$(git rev-parse --show-toplevel)"
    TARGETS="$(bazel query 'kind(rule, rdeps(//..., set(<MODIFIED_FILES>), 1))' --keep_going 2>/dev/null)"
    if [ -n "$TARGETS" ]; then
        bazel build $TARGETS
@@ -40,6 +43,7 @@ After changing Rust code (`*.rs`) follow these steps in order:
    Fix all build errors.
 4. **Test** the directly affected bazel tests by running the following from the root of the repository:
    ```
+   cd "$(git rev-parse --show-toplevel)"
    TESTS="$(bazel query 'kind(".*_test|test_suite", kind(rule, rdeps(//..., set(<MODIFIED_FILES>), 2)))' --keep_going 2>/dev/null)"
    if [ -n "$TESTS" ]; then
        bazel test --test_output=errors $TESTS