Fiken API client and OAuth2 for Gov0.1.0

Extracted from gcbill, where it was internal/fiken and internal/fikenauth,
so adaa and sokkel-billing can use the same client instead of each
carrying its own.

The login command named when a grant cannot be renewed is now injected
(Source.LoginCommand): it was hardcoded to gcbill's, which would have sent
every other caller's operator to a command that does not exist.

1 files changed, 3 insertions, 0 deletions

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..8305bbb
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module simenandre.no/fiken
+
+go 1.26.8