feat: remove dead code

[henrypeters]

Here's what was done and why:

Dead code removed:

• get_status() — hardcoded SubscriptionStatus::Active, never exercised any logic
• get_content() — hardcoded ContentType::Paid, same problem

Both were pure stubs that returned constants. They added Wasm surface without testing anything.

What replaced them:

┌─────────────────┬─────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ New entry point │ Purpose │
├─────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ is_active() │ Kept — it has real logic (equality check) │
├─────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ error_code() │ New — proves MyfansError is importable from myfans-lib and its discriminants are stable across crate boundaries │
├─────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ content_code() │ New — same for ContentType │
└─────────────────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

Tests added (4 total):

• active_is_active — positive case for is_active
• non_active_statuses_are_not_active — covers all 3 non-active variants (Pending, Cancelled, Expired)
• error_codes_are_stable — asserts all 15 MyfansError discriminants match their documented values; this acts as a regression guard — if anyone renumbers an error
  code in myfans-lib, this test breaks immediately
• content_type_codes_are_stable — same for ContentType

No regressions: the crate's public contract interface still exports is_active, and the test patterns match the existing repo style (inline Env::default() +
register_contract + Client::new).

closes #621

[drips-wave]

@henrypeters Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits