Read feature, release workflow (v0.3.0)

- Read button (desktop and web): reads the tag now, bypassing the status
  cache, and puts its first link or text record into the input field so it
  can be copied to another tag. POST /api/read in the web version.
- Raw memory: every 4-byte page from page 0 (UID, lock bytes, CC, data) in
  hex and ASCII, collapsed by default.
- Content now shows the records and the note together (a locked tag showed
  only "read-only" before); read failures are flagged with read_failed
  instead of matching message text.
- .gitea/workflows/release.yml: on a v* tag, tests and clippy, then Linux
  (ubuntu-22.04, glibc 2.35) and Windows (MinGW cross-build) packages
  attached to the tag's release with its CHANGELOG.md section.
- README: reading, why the reader program runs on the reader's machine,
  releases.

.gitea/workflows/release.yml

@@ -0,0 +1,88 @@
+# Release builds on git.b4l.co.th (Gitea Actions).
+#
+# On a v* tag: tests, then the Linux and Windows x86_64 binaries (desktop app
+# and web version), packaged and attached to the tag's release (created when
+# missing, text from CHANGELOG.md). On demand (workflow_dispatch) the same
+# packages become the artifact `nfc-writer-packages` instead.
+#
+# Linux is built on ubuntu-22.04 so the binary needs only glibc 2.35 (Debian 12,
+# Ubuntu 22.04 and newer). Windows is cross-built with MinGW-w64. macOS has no
+# runner here: build it on a Mac (README, "Build and run").
+name: Release
+
+on:
+  push:
+    tags: ['v*']
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUST_TOOLCHAIN: "1.98.1"
+
+jobs:
+  release:
+    runs-on: ubuntu-22.04
+    timeout-minutes: 60
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: System packages
+        run: |
+          SUDO=$(command -v sudo || true)
+          $SUDO apt-get update -qq
+          $SUDO apt-get install -y -qq curl ca-certificates gcc libc6-dev pkg-config \
+            libpcsclite-dev gcc-mingw-w64-x86-64 zip python3
+
+      - name: Rust toolchain
+        run: |
+          if ! command -v rustup >/dev/null && [ ! -x "$HOME/.cargo/bin/rustup" ]; then
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal --default-toolchain none
+          fi
+          export PATH="$HOME/.cargo/bin:$PATH"
+          echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
+          rustup toolchain install "$RUST_TOOLCHAIN" --profile minimal -c clippy -t x86_64-pc-windows-gnu
+          rustup default "$RUST_TOOLCHAIN"
+          rustc --version
+
+      - name: Tests and clippy
+        run: |
+          cargo test --locked
+          cargo clippy --locked --all-targets -- -D warnings
+
+      - name: Build
+        run: |
+          cargo build --locked --release
+          cargo build --locked --release --target x86_64-pc-windows-gnu
+
+      - name: Package
+        run: |
+          case "$GITHUB_REF" in
+            refs/tags/*) version="$GITHUB_REF_NAME" ;;
+            *) version="dev-${GITHUB_SHA::7}" ;;
+          esac
+          mkdir -p dist
+          linux="nfc-writer-$version-linux-x86_64"
+          mkdir "$linux"
+          cp target/release/nfc-writer target/release/nfc-writer-web README.md "$linux/"
+          tar czf "dist/$linux.tar.gz" "$linux"
+          windows="nfc-writer-$version-windows-x86_64"
+          mkdir "$windows"
+          cp target/x86_64-pc-windows-gnu/release/nfc-writer.exe \
+             target/x86_64-pc-windows-gnu/release/nfc-writer-web.exe README.md "$windows/"
+          zip -qr "dist/$windows.zip" "$windows"
+          ls -l dist
+
+      - name: Attach to the release
+        if: startsWith(github.ref, 'refs/tags/v')
+        env:
+          TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: python3 .gitea/scripts/release-attach.py dist/*
+
+      - name: Artifact (on-demand runs)
+        if: "!startsWith(github.ref, 'refs/tags/v')"
+        uses: https://github.com/christopherHX/gitea-upload-artifact@v4
+        with:
+          name: nfc-writer-packages
+          path: dist/