fix(ci): resolve Fuzz workflow failures

Root Cause Analysis:
- GitHub Action 'dtolnay/rust-action' does not exist
- Correct action is 'dtolnay/rust-toolchain'
- Fuzz directory not excluded from workspace causing build conflicts

Changes Made:

1. Fixed GitHub Action References (.github/workflows/fuzz.yml):
   - Changed 'dtolnay/rust-action@nightly' → 'dtolnay/rust-toolchain@nightly'
   - Applied to both 'fuzz' and 'extended-fuzz' jobs (2 occurrences)
   - Verified against official dtolnay/rust-toolchain documentation

2. Fixed Workspace Configuration (Cargo.toml):
   - Added 'fuzz' to workspace.exclude array
   - cargo-fuzz requires isolated workspace to function properly
   - Prevents 'current package believes it's in a workspace' error

Verification:
- Successfully built fuzz target 'fuzz_frame_parser' with cargo +nightly
- All 5 fuzz targets verified to exist and compile:
  - fuzz_frame_parser
  - fuzz_dht_message
  - fuzz_crypto
  - fuzz_padding
  - fuzz_tree_hash
- No other workflows affected by this change

Impact:
- All Fuzz workflow jobs should now pass
- Weekly scheduled fuzzing will execute correctly
- Manual workflow_dispatch fuzzing enabled

References:
- https://github.com/dtolnay/rust-toolchain
- cargo-fuzz best practices for workspace configuration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: doublegate

.github/workflows/fuzz.yml

@@ -55,7 +55,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Rust nightly
-        uses: dtolnay/rust-action@nightly
+        uses: dtolnay/rust-toolchain@nightly
         with:
           components: llvm-tools-preview
 
@@ -148,7 +148,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Install Rust nightly
-        uses: dtolnay/rust-action@nightly
+        uses: dtolnay/rust-toolchain@nightly
         with:
           components: llvm-tools-preview
 

Cargo.toml

@@ -19,7 +19,8 @@ members = [
 ]
 
 # XDP crate excluded from default - requires special build
-exclude = ["crates/wraith-xdp"]
+# Fuzz targets excluded - cargo-fuzz manages its own workspace
+exclude = ["crates/wraith-xdp", "fuzz"]
 
 [workspace.package]
 version = "1.1.0"