Rewrite maifetch in GnuCOBOL

[Errordog2]

/claim #1

This PR rewrites maifetch in GnuCOBOL for the latest maintainer direction requesting a GnuCOBOL implementation.

Scope:

• Replaces the Go module with a GnuCOBOL CLI entrypoint in src/maifetch.cob.
• Preserves the original config priority: CLI > environment > config file > defaults.
• Supports --access-token/-a/-t, --logo-size/-l, --score-count/-s, and --config-file/-c.
• Fetches MaiTea /api/v1/profiles and /api/v1/plays via authenticated curl requests, then formats profile and recent-score output from those API responses.
• Adds fixture-mode test hooks (MAIFETCH_PROFILE_FIXTURE, MAIFETCH_PLAYS_FIXTURE) so CI can validate output without live credentials.
• Adds a GnuCOBOL GitHub Actions workflow that installs gnucobol and runs make test.

Validation:

• git diff --check passed locally.
• git diff --cached --check passed locally.
• tests/run-fixture-test.sh is staged executable (100755).
• Local make test is not runnable on this Windows machine because cobc is not installed; the included CI installs GnuCOBOL on Ubuntu and runs the fixture test.

Maintainer LLM note: files created or rewritten with LLM assistance include an OpenAI GPT-5 Codex note at the top, following the issue instruction.

[Errordog2]

Follow-up: I fixed the GnuCOBOL CI failure from the first run by using GnuCOBOL's direct ACCEPT ... FROM ENVIRONMENT identifier form for environment lookup. The new branch head is 807e046, and the GnuCOBOL workflow is now passing: https://github.com/Errordog2/maifetch/actions/runs/27433729517