chore: rename the project to ghglance

The Marketplace rejects ghstats as an action name, so the repo, Go module,
binary, and action share the name ghglance instead. The demo workflow keeps
reading the existing GHSTATS_TOKEN repo secret.

docs/code-standards.md

@@ -66,7 +66,7 @@ Never write comments that describe what well-named code does (`// increment coun
 ## Testing
 
 - Unit tests in the same package, no mocking of http.Client — we test rendering and pure helpers.
-- Network tests are omitted; integration verification is manual (`./ghstats -token ...`).
+- Network tests are omitted; integration verification is manual (`./ghglance -token ...`).
 - `go vet ./...` clean before every commit.
 
 ## Commit conventions