Add notifications for target maintainers (#10)

This adds a feature where maintainers can add themselves to an array in the source to receive notifications whenever the target fails.

The way this works is via GitHub, I created a new repository https://github.com/Noratrieb/does-it-build-notifications where an app will create issues that ping the respective users. This is the easiest option for me and also fits nicely into people's workflows on GitHub.

Whenever a target fails, an issue is created for it. This issue is kept open (with a new comment every day that it continues to fail), and then closed when the target builds again.

migrations/20251110170025_notifications.sql

@@ -0,0 +1,10 @@
+-- Add migration script here
+
+CREATE TABLE notification_issues(
+    "issue_number" INTEGER PRIMARY KEY,
+    "status" TEXT NOT NULL, -- open/closed
+    "first_failed_nightly" TEXT NOT NULL,
+    "target" TEXT NOT NULL
+) STRICT;
+
+CREATE INDEX notification_issues_target on notification_issues("target", "status");