chore: add push/PR CI, drop unused windows dep, refresh docs

Add a CI workflow running fmt, clippy with warnings denied, and the test
suite on every push and pull request. Remove the unused workspace windows
dependency now that only windows-sys is used. Update the README architecture
name and Java harness reference, clarify the plans gitignore comment, and
carry the code-reviewer agent memory.

.github/workflows/ci.yml

@@ -0,0 +1,27 @@
+name: ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    name: fmt-clippy-test-windows-x64
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain (pinned by rust-toolchain.toml)
+        uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: rustfmt, clippy
+
+      - uses: Swatinem/rust-cache@v2
+
+      - run: cargo fmt --all -- --check
+      - run: cargo clippy --workspace --all-targets -- -D warnings
+      - run: cargo test --workspace