Integration tests: drive the real --web server end-to-end (2.1)

Unit tests cover parsers/resolvers but not whether the axum handlers,
SQLite layer, and config persistence actually wire together. New
tests/api.rs spawns the compiled binary in --web mode against a scratch
library dir and exercises the real HTTP API the way a browser does —
no network / yt-dlp needed (every endpoint here is local state).

Coverage: index + /api/library served; ETag conditional GET → 304;
settings round-trip (POST → GET reflects → config.toml on disk updated);
folder CRUD + the self-parent cycle guard (→ 400); notes upsert/delete;
channel-options store + is_empty() clear; backup/db returns a real
SQLite file.

HTTP via curl (transparently handles the server's gzip + chunked
encoding; already a CI dependency) with a graceful skip if curl is
absent. Each test gets its own server, port (bind :0 to grab a free
one), and tempdir, so they run in parallel and clean up on drop.

Added .forgejo/workflows/test.yml so `cargo test` (unit + integration)
runs on every push/PR — the release workflow only fired on tags. 105
tests pass (98 unit + 7 integration).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.forgejo/workflows/test.yml

@@ -0,0 +1,40 @@
+# Build + test on every push / PR. The release workflow only fires on
+# tags, so this is the everyday safety net: it compiles the binary and
+# runs the full suite, including the tests/api.rs integration tests that
+# spawn the real `--web` server and drive its HTTP API.
+name: test
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test:
+    runs-on: docker
+    container:
+      image: rust:1.85-bookworm
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install build dependencies
+        # libxcb headers are needed to *link* the eframe/winit GUI even
+        # though the integration tests only run the headless --web server.
+        # curl is what the integration tests use as their HTTP client.
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends \
+            libxcb1-dev libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev \
+            libxkbcommon-dev curl ca-certificates
+
+      - name: Cache cargo registry + build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: cargo-test-${{ runner.os }}-${{ hashFiles('Cargo.lock') }}
+
+      - name: Test (unit + integration)
+        run: cargo test --locked