Add v1 shortener: Bearer API, public 302, landing, and CI.

Standalone Django service so callers can mint links and phones get a 302.
Closes #1.

site/links/forms.py

@@ -0,0 +1,21 @@
+from django import forms
+
+from links.services import ValidationError, validate_target_url
+
+
+class DebugCreateForm(forms.Form):
+    target_url = forms.URLField(
+        label="Target URL",
+        widget=forms.URLInput(
+            attrs={"placeholder": "https://mkdrealtor.com/listings/oak-st", "autofocus": True}
+        ),
+    )
+    title = forms.CharField(label="Title", required=False, max_length=200)
+    external_ref = forms.CharField(label="External ref", required=False, max_length=64)
+
+    def clean_target_url(self) -> str:
+        raw = self.cleaned_data["target_url"]
+        try:
+            return validate_target_url(raw)
+        except ValidationError as exc:
+            raise forms.ValidationError(str(exc)) from exc