fix: share Happ generation and correct protocol labels

Move the reusable generator into commons, add Netherlands display metadata, and label Hysteria links by protocol without changing URI parameters.

Disclosure: I'm an AI assistant helping Vladimir Eremin; I'm not Vladimir Eremin.

actions/utils/generate-happ-subscriptions.py

@@ -0,0 +1,29 @@
+"""Build and run the shared Happ subscription generator."""
+import os
+import shutil
+from engine.descriptor import Meta, Arg
+
+METADATA = Meta(summary="Generate .psub files from a JSON config via the happ generator (docker).",
+                args=[Arg("input_json", "input JSON config"), Arg("output_dir", "output directory")])
+IMAGE = "happ-subscription-generator"
+
+def run(ctx, args):
+    log = ctx.log
+    src_dir = os.path.join(ctx.paths.commons, "assets", "happ-subscription-generator")
+    inp, out = os.path.realpath(args.input_json), os.path.realpath(args.output_dir)
+    # GNU realpath (bash) fails unless all but the last component exist — without this
+    # guard a mistyped path reaches `docker run -v`, which creates it root-owned.
+    for label, p in (("input_json", inp), ("output_dir", out)):
+        parent = os.path.dirname(p)
+        if not os.path.isdir(parent):
+            log.error(f"Cannot resolve {label}: no such directory: {parent}")
+            raise SystemExit(1)
+    if not shutil.which("docker"):
+        log.error("docker is not installed or not in PATH.")
+        raise SystemExit(1)
+    log.info(f"Building {IMAGE}...")
+    ctx.sys.run(["docker", "build", "-t", IMAGE, src_dir], check=True)
+    log.info(f"Running generator: {inp} -> {out}")
+    ctx.sys.run(["docker", "run", "--rm", "-v", f"{inp}:/app/input.json:ro",
+                 "-v", f"{out}:/app/output:rw", IMAGE, "/app/input.json", "/app/output"], check=True)
+    log.success("Subscription generation completed.")