Add optimization docs, workspace lints, and pre-commit hooks

- Add docs/OPTIMIZATIONS.md: catalog of 14 optimization passes with
  status tracking and implementation roadmap
- Configure workspace-level clippy and rustc lints in Cargo.toml
- Add clippy.toml and deny.toml for clippy thresholds and dependency
  auditing (licenses, advisories, bans)
- Set up pre-commit hook: cargo fmt, dprint, clippy, cargo deny,
  cargo machete
- Update Justfile with deny/machete targets, dprint in fmt checks

deny.toml

@@ -0,0 +1,35 @@
+[advisories]
+ignore = [
+    # wasmtime v31 known issues -- will resolve when upgrading wasmtime
+    { id = "RUSTSEC-2025-0046", reason = "wasmtime v31: fd_renumber panic" },
+    { id = "RUSTSEC-2025-0118", reason = "wasmtime v31: shared memory unsoundness" },
+    { id = "RUSTSEC-2026-0006", reason = "wasmtime v31: f64.copysign segfault" },
+    { id = "RUSTSEC-2026-0020", reason = "wasmtime v31: WASI resource exhaustion" },
+    { id = "RUSTSEC-2026-0021", reason = "wasmtime v31: fields instance panic" },
+    # Unmaintained transitive deps from wasmtime/rustyline
+    { id = "RUSTSEC-2025-0057", reason = "fxhash: transitive dep, no alternative" },
+    { id = "RUSTSEC-2024-0436", reason = "paste: transitive dep, no alternative" },
+]
+
+[licenses]
+allow = [
+    "MIT",
+    "Apache-2.0",
+    "Apache-2.0 WITH LLVM-exception",
+    "BSD-2-Clause",
+    "BSD-3-Clause",
+    "BSL-1.0",
+    "Unicode-3.0",
+    "Zlib",
+]
+confidence-threshold = 0.8
+
+[bans]
+multiple-versions = "warn"
+wildcards = "deny"
+
+[sources]
+unknown-registry = "deny"
+unknown-git = "deny"
+allow-registry = ["https://github.com/rust-lang/crates.io-index"]
+allow-git = []