Revert --release tests; optimize insta/similar in dev profile instead

Full --release builds are 3-5x slower due to compilation overhead.
Instead, follow oxc's approach: optimize only the snapshot testing
dependencies (insta, similar) at opt-level=3 in dev profile. This
speeds up snapshot diffing without penalizing compile times.

https://claude.ai/code/session_01MM41gBUbWHBiX8Skve91rG

Author: claude

.github/workflows/ci.yml

@@ -127,10 +127,10 @@ jobs:
       # Must run after setup-node so correct native binaries are installed
       - run: pnpm install
 
-      - run: cargo test --release --target ${{ matrix.target }}
+      - run: cargo test --target ${{ matrix.target }}
         if: ${{ matrix.os != 'ubuntu-latest' }}
 
-      - run: cargo-zigbuild test --release --target x86_64-unknown-linux-gnu.2.17
+      - run: cargo-zigbuild test --target x86_64-unknown-linux-gnu.2.17
         if: ${{ matrix.os == 'ubuntu-latest' }}
 
   test-musl:
@@ -175,7 +175,7 @@ jobs:
           corepack enable
           pnpm install
 
-      - run: cargo test --release
+      - run: cargo test
 
   fmt:
     name: Format and Check Deps

Cargo.toml

@@ -167,6 +167,13 @@ ignored = [
 # and we don't rely on it for debugging that much.
 debug = false
 
+# Optimize snapshot testing dependencies in dev/test builds.
+# Snapshot diffing (insta + similar) is CPU-intensive; optimizing them
+# speeds up test runs without the compile-time cost of a full release build.
+[profile.dev.package]
+insta.opt-level = 3
+similar.opt-level = 3
+
 [profile.release]
 # Configurations explicitly listed here for clarity.
 # Using the best options for performance.