feat(tracing): add performance profiling via tracing crate

Wire up the existing --profile flag with tracing-subscriber to emit
span timings on stderr. Supports MOZART_LOG env var override and
verbose-level-aware filtering. No subscriber is installed when
--profile is off, keeping tracing macros zero-cost.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 8d93856..9d0691a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,6 +31,8 @@ sha1 = "0.10"
 tar = "0.4"
 tempfile = "3.25.0"
 tokio = { version = "1.49.0", features = ["full"] }
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
 zip = { version = "2", default-features = false, features = ["deflate"] }
 assert_cmd = "2"
 predicates = "3"