Update Shikimori domain from shikimori.one to shikimori.io

[noctuum]

Issue

Shikimori has changed their primary domain from shikimori.one to shikimori.io. The old domain currently redirects, but API URLs, OAuth URLs, and documentation links should be updated to the new canonical domain.

Affected locations

• trackma/lib/libshikimori.py — url, auth_url, api_url class attributes (lines 93-95) and docstring (line 32)
• trackma/utils.py — OAuth authorize URL (line 170)
• README.md — website link (line 25)

Proposed fix

Replace all occurrences of shikimori.one with shikimori.io.