feat: close stage 0-2 audit groundwork

Remove legacy SDL/OpenGL adapters from the workspace and introduce winit/Vulkan adapter boundaries for the rendered composition root.

Add reproducible toolchain and xtask CI coverage for formatting, tests, clippy, docs, policy, deny, acceptance auditing, and hosted OS matrix evidence.

Strengthen Stage 1 data contracts with byte-first paths, VFS hardening, structured diagnostics, RsLi writer/edit scaffolding, corpus reporting, and resource error classification.

Advance Stage 2 asset preparation by moving mission loading through assets/runtime boundaries, materializing prototype graph data, preserving provenance, and adding inspection/viewer integration.

Record the Stage 0-2 audit input, acceptance roadmap, coverage updates, and documentation notes for follow-up evidence.

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: fparkan-ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  stage0-matrix:
+    name: Stage 0-2 CI (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - windows-latest
+          - macos-latest
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain-file: rust-toolchain.toml
+      - name: Install cargo-deny
+        run: cargo install cargo-deny --locked
+      - name: Run canonical CI gate
+        run: cargo xtask ci
+      - name: Upload acceptance evidence
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: stage-0-2-acceptance-${{ matrix.os }}
+          path: target/fparkan/acceptance/stage-0-2-audit.json
+          if-no-files-found: ignore