Onboard onto bakery: bakery.toml + dev/beta/release CI, relocate content paths

Adds bakery.toml (binaries, license_file, desktop_file, data_archive for
the guide content directory) and the standard three-track CI workflows,
mirroring the pattern used across the rest of the bread ecosystem.

Also fixes the tour/troubleshooting-symptoms loaders (tour.rs,
troubleshoot.rs) to check the bakery-writable user content root
(~/.local/share/breadhelp/content) before the system path a pacman
package would have used — the main ContentStore already did this via
user_content_root(), these two were the last holdouts still hardcoded to
/usr/share/breadhelp only.

.forgejo/workflows/release.yml

@@ -0,0 +1,67 @@
+name: release
+
+on:
+  push:
+    tags: ["v*"]
+
+jobs:
+  build:
+    runs-on: [self-hosted, hestia]
+    steps:
+      - name: checkout
+        run: |
+          set -euo pipefail
+          rm -rf src && mkdir src
+          git clone --branch "${GITHUB_REF_NAME}" --depth 1 \
+            "https://git.breadway.dev/${GITHUB_REPOSITORY}.git" src
+
+      - name: build
+        run: cd src && cargo build --release --locked
+
+      - name: test
+        run: cd src && cargo test --release --locked
+
+      - name: prepare artifacts
+        run: |
+          set -euo pipefail
+          VERSION="${GITHUB_REF_NAME#v}"
+          PKG_DIR="/srv/breadway-dl/breadhelp/${VERSION}"
+          mkdir -p "${PKG_DIR}"
+          cp "src/target/release/breadhelp" "${PKG_DIR}/breadhelp-x86_64"
+          strip "${PKG_DIR}/breadhelp-x86_64"
+          sha256sum "${PKG_DIR}/breadhelp-x86_64" | awk '{print $1}' \
+            > "${PKG_DIR}/breadhelp-x86_64.sha256"
+          cp src/packaging/breadhelp.desktop "${PKG_DIR}/"
+          cp src/LICENSE "${PKG_DIR}/"
+          tar czf "${PKG_DIR}/content.tar.gz" -C src content
+          cp src/bakery.toml "${PKG_DIR}/bakery.toml"
+          ln -sfn "${VERSION}" "/srv/breadway-dl/breadhelp/latest"
+
+      - name: regenerate index.json
+        env:
+          MINISIGN_SEC_KEY: ${{ secrets.BAKERY_MINISIGN_SEC_KEY_PATH }}
+        run: |
+          set -euo pipefail
+          if [ -z "${MINISIGN_SEC_KEY:-}" ]; then
+            echo "::error::BAKERY_MINISIGN_SEC_KEY_PATH secret not set — refusing to regenerate index.json unsigned (would leave a stale signature mismatched against fresh content and break bakery for everyone)"
+            exit 1
+          fi
+          rm -rf /tmp/bread-ecosystem-ci-* 2>/dev/null || true
+          ECOSYSTEM_CI_DIR="$(mktemp -d /tmp/bread-ecosystem-ci-XXXXXX)"
+          git clone https://git.breadway.dev/Breadway/bread-ecosystem.git "${ECOSYSTEM_CI_DIR}"
+          bash "${ECOSYSTEM_CI_DIR}/scripts/gen-index.sh"
+          rm -rf "${ECOSYSTEM_CI_DIR}"
+
+      - name: upload to GitHub Release
+        env:
+          GH_TOKEN: ${{ secrets.GH_RELEASE_TOKEN }}
+        run: |
+          set -euo pipefail
+          VERSION="${GITHUB_REF_NAME#v}"
+          PKG_DIR="/srv/breadway-dl/breadhelp/${VERSION}"
+          gh release create "${GITHUB_REF_NAME}" --repo Breadway/breadhelp \
+            --title "breadhelp v${VERSION}" --generate-notes 2>/dev/null || true
+          gh release upload "${GITHUB_REF_NAME}" --repo Breadway/breadhelp \
+            "${PKG_DIR}/breadhelp-x86_64" \
+            "${PKG_DIR}/breadhelp-x86_64.sha256" \
+            --clobber