fix: add missing src/lib.rs and runtime dependencies

The test suite was unable to compile because the crate had no library entry
point and three runtime dependencies were used in the implementation but not
declared in Cargo.toml.

- src/lib.rs: add library root exporting `pub mod bridge`
- Cargo.toml: add walkdir, chrono (with serde feature), ureq (with json feature)

45 tests now pass across e2e_test, aspect_test, property_test, and lib.

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

Author: hyperpolymath

Cargo.toml

@@ -15,6 +15,9 @@ serde_json = "1"
 toml = "0.8"
 semver = "1"
 anyhow = "1.0"
+walkdir = "2"
+chrono = { version = "0.4", features = ["serde"] }
+ureq = { version = "2", features = ["json"] }
 
 [dev-dependencies]
 proptest = "1"

src/lib.rs

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: PMPL-1.0-or-later
+// Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
+//! patch-bridge — CVE mitigation lifecycle tool.
+//!
+//! Tracks the path from vulnerability disclosure through to verified
+//! remediation, with reachability analysis to prioritise real exposure.
+
+pub mod bridge;