ci: lint the whole workspace with clippy and add cargo-deny (#407)

## Summary

CI currently runs `cargo clippy -- --D warnings`, which only lints the
root crate with default targets — the `ffi`, `cli` and `uniffi` crates
were never linted. This PR:

- **Widens the CI clippy invocation** to `cargo clippy --workspace
--all-targets -- -D warnings` (and fixes the `--D` → `-D` flag
spelling).
- **Fixes all 49 clippy findings** this surfaced, all in
`ffi/src/lib.rs`:
- Missing `# Safety` doc sections on the 16 online ciphertext FFI
functions (docs added following the file's existing style, including
notes that `OnlineEncryptorLastChunk`/`OnlineDecryptorLastChunk` consume
the handle).
- Doc list continuation-line indentation
(`doc_overindented_list_items`).
  - Redundant `as *const u8` pointer casts.
  - Manual `% 4 != 0` replaced with `is_multiple_of`.
- For the `mut_mutex_lock` warnings in the chunk functions: take a
shared reference to the mutex and keep `lock()` (like the read-side
accessors) instead of fabricating a `&mut` from the raw handle — the
handle can be used from multiple threads, so the mutex must actually be
acquired.
- **Adds a `cargo_deny` CI job** (advisories, bans, licenses, sources),
installing cargo-deny with `cargo install --locked` — same convention as
cargo-fuzz in the extended fuzzing workflow, no third-party action.
- **Migrates `deny.toml`** from the pre-0.14 schema (which current
cargo-deny rejects) to the current one, keeping the same policy. Two
adjustments so the check passes on today's dependency tree:
- `Zlib` added to the license allow-list (`foldhash`, pulled in via
`blahaj`).
- `RUSTSEC-2024-0436` ignored with a comment: `paste` is an archived
proc-macro dependency; replacing it (e.g. with `pastey`) is left as a
follow-up.
- **Refreshes `Cargo.lock`** to latest compatible versions (~40 bumps,
including zeroize 1.9, rand 0.10.2, getrandom 0.4.3; also consolidates
duplicate crate versions).
- **Migrates the CLI off the base64 crate.** The CLI pinned base64 0.11
(2020); it now uses the library's own
`utils::base64_encode/base64_decode` helpers (which use base64 0.22
internally) and the direct dependency is dropped.
- **Upgrades uniffi from 0.31 to 0.32.** Bindings are generated at build
time, so CI regenerates them with the matching uniffi version. One
adaptation was needed: uniffi 0.32 maps borrowed `&[u8]` arguments to
`java.nio.ByteBuffer` in Kotlin (zero-copy lowering), which would have
broken every Kotlin consumer expecting `ByteArray`. The exported
functions now take owned `Vec<u8>`, which keeps the Kotlin API on
`ByteArray`; Swift (`Data`) and Python (`bytes`) are unaffected either
way.

## Testing

- `cargo clippy --workspace --all-targets -- -D warnings` — clean
- `cargo fmt --all -- --check` — clean
- `cargo deny check` — advisories ok, bans ok, licenses ok, sources ok
- `cargo test --workspace` (excluding fuzz targets) — 134 passed, 0
failed

Author: mmorrissette-devolutions

.github/workflows/ci.yml

@@ -189,6 +189,19 @@ jobs:
       - uses: actions/checkout@v6
       - uses: ./.github/workflows/formatting/rust
 
+  #### DEPENDENCY AUDIT ####
+  cargo_deny:
+    runs-on: "ubuntu-22.04"
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install cargo-deny
+        run: cargo install cargo-deny --locked
+
+      - name: Check dependencies
+        run: cargo deny check
+
   #### FUZZ TESTING ####
   quick_fuzz:
     runs-on: "ubuntu-22.04"

.github/workflows/formatting/rust/action.yml

@@ -20,4 +20,4 @@ runs:
     - name: Check Clippy
       working-directory: ./
       shell: bash
-      run: cargo clippy -- --D warnings
+      run: cargo clippy --workspace --all-targets -- -D warnings