feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/fugit/.github/workflows/build.yml

@@ -0,0 +1,130 @@
+name: Build
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - staging
+      - trying
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  # Run cargo fmt --check, includes macros/
+  style:
+    name: style
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+          components: rustfmt
+
+      - name: cargo fmt --check
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  # Compilation check
+  check:
+    name: check
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - x86_64-unknown-linux-gnu
+        toolchain:
+          - stable
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Cache cargo dependencies
+        uses: actions/cache@v4
+        with:
+          path: |
+            - ~/.cargo/bin/
+            - ~/.cargo/registry/index/
+            - ~/.cargo/registry/cache/
+            - ~/.cargo/git/db/
+          key: ${{ runner.OS }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+            ${{ runner.OS }}-cargo-
+
+      - name: Cache build output dependencies
+        uses: actions/cache@v4
+        with:
+          path: target
+          key: ${{ runner.OS }}-build-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-build-${{ hashFiles('**/Cargo.lock') }}
+            ${{ runner.OS }}-build-
+
+      - name: Install Rust ${{ matrix.toolchain }} with target (${{ matrix.target }})
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.toolchain }}
+          target: ${{ matrix.target }}
+          override: true
+
+      - name: cargo check
+        uses: actions-rs/cargo@v1
+        with:
+          use-cross: false
+          command: check
+          args: --target=${{ matrix.target }}
+
+  tests:
+    name: tests
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - x86_64-unknown-linux-gnu
+        toolchain:
+          - stable
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Cache cargo dependencies
+        uses: actions/cache@v4
+        with:
+          path: |
+            - ~/.cargo/bin/
+            - ~/.cargo/registry/index/
+            - ~/.cargo/registry/cache/
+            - ~/.cargo/git/db/
+          key: ${{ runner.OS }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-cargo-
+
+      - name: Cache build output dependencies
+        uses: actions/cache@v4
+        with:
+          path: target
+          key: ${{ runner.OS }}-build-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.OS }}-build-
+
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.toolchain }}
+          target: ${{ matrix.target }}
+          override: true
+
+      - uses: actions-rs/cargo@v1
+        with:
+          use-cross: false
+          command: test
+          args: --target=${{ matrix.target }}

vendor/fugit/.github/workflows/changelog.yml

@@ -0,0 +1,28 @@
+# Check that the changelog is updated for all changes.
+#
+# This is only run for PRs.
+
+on:
+  pull_request:
+    # opened, reopened, synchronize are the default types for pull_request.
+    # labeled, unlabeled ensure this check is also run if a label is added or removed.
+    types: [opened, reopened, labeled, unlabeled, synchronize]
+
+name: Changelog
+
+jobs:
+  changelog:
+    name: Changelog
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v4
+
+      - name: Check that changelog updated
+        uses: dangoslen/changelog-enforcer@v3
+        with:
+          changeLogPath: CHANGELOG.md
+          skipLabels: 'needs-changelog, skip-changelog'
+          missingUpdateErrorMessage: 'Please add a changelog entry in the CHANGELOG.md file.'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}