fix(ci): commit Cargo.lock for reproducible builds (#1123)

## Summary

- Remove `Cargo.lock` from `.gitignore` and commit it to the repo
- Remove the `cargo generate-lockfile` step from CI audit job
- Prevents spontaneous CI breakage when upstream crates publish new
versions

**Root cause:** `Cargo.lock` was gitignored, so CI generated a fresh
lockfile each run via `cargo generate-lockfile`. When `python3-dll-a`
0.2.15 was published to crates.io, the fresh resolve picked it up but
the cargo-vet exemption still listed 0.2.14 — breaking main without any
code change.

**Fix:** Committing `Cargo.lock` pins exact versions. Dependency bumps
become explicit (`cargo update`) and show up in diffs, so cargo-vet
exemptions can be updated in the same PR.

## Test plan

- [x] `cargo vet --locked` passes locally
- [ ] CI audit job passes without `generate-lockfile` step

Author: chaliy

.github/workflows/ci.yml

@@ -50,9 +50,6 @@ jobs:
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable
 
-      - name: Generate lockfile
-        run: cargo generate-lockfile
-
       - name: Security audit (cargo-audit)
         uses: rustsec/audit-check@v2.0.0
         with:

.gitignore

@@ -1,6 +1,5 @@
 # Rust
 /target/
-Cargo.lock
 
 # Environment
 .env