Use single-threaded hashmap instead of dashmap

Address performance regressions

Cargo.lock

@@ -442,7 +442,6 @@ dependencies = [
  "criterion",
  "dagrs",
  "dagx-macros",
- "dashmap",
  "futures",
  "futures-executor",
  "parking_lot",
@@ -462,20 +461,6 @@ dependencies = [
  "syn 2.0.106",
 ]
 
-[[package]]
-name = "dashmap"
-version = "6.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5041cc499144891f3790297212f32a74fb938e5136a14943f338ef9e0ae276cf"
-dependencies = [
- "cfg-if",
- "crossbeam-utils",
- "hashbrown",
- "lock_api",
- "once_cell",
- "parking_lot_core",
-]
-
 [[package]]
 name = "either"
 version = "1.15.0"
@@ -656,12 +641,6 @@ dependencies = [
  "crunchy",
 ]
 
-[[package]]
-name = "hashbrown"
-version = "0.14.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
-
 [[package]]
 name = "hermit-abi"
 version = "0.5.2"