ci: use Jsonnet for YAML configuration generation

Because the two kinds of pipelines were very similar, I used Jsonnet to
factorise the definitions.

This means I have to switch the configuration file in my settings, and
enable Jsonnet files.

.drone.jsonnet

@@ -0,0 +1,45 @@
+local Pipeline(isDev) = {
+  kind: "pipeline",
+  name: if isDev then "deploy-dev" else "deploy-prod",
+  # Dev ignores "master", prod only triggers on "master"
+  trigger: { branch: { [if isDev then "exclude" else "include"]: [ "master" ] } },
+  # We want to clone the submodules, which isn't done by default
+  clone: { disable: true },
+  steps: [
+    {
+      name: "clone",
+      image: "plugins/git",
+      recursive: true,
+    },
+    {
+      name: "build",
+      image: "klakegg/hugo",
+      commands: [
+        "hugo version",
+        # If dev, include drafts and future articles, change base URL
+        "hugo --minify" + if isDev then " -D -F -b https://dev.belanyi.fr" else "",
+      ],
+      [if !isDev then "environment"]: { HUGO_ENV: "production" }
+    },
+    {
+      name: "deploy",
+      image: "appleboy/drone-scp",
+      settings: {
+        source: "public/*",
+        strip_components: 1, # Remove 'public/' suffix from file paths
+        rm: true, # Remove previous files from target directory
+        host: { from_secret: "ssh_host" },
+        target: { from_secret: "ssh_target" + if isDev then "_dev" else "" },
+        username: { from_secret: "ssh_user" },
+        key: { from_secret: "ssh_key" },
+        port: { from_secret: "ssh_port" },
+      },
+    },
+  ]
+};
+
+
+[
+  Pipeline(false),
+  Pipeline(true),
+]