Add opt-in support for team members' limit permissions

[tastybento]

Fixes #241 (canonical ticket for #164 and part of #147's fallout).

What

New config option, off by default:

apply-member-limit-perms: false

When enabled:

• A team member's login merges their <gamemode>.island.limit.* permissions into the island's limits — the highest value wins, nothing is cleared.
• The owner's login keeps the existing clear-and-recalculate behaviour, then merges in the permissions of all online team members, so an owner relog doesn't wipe member contributions while they're around.
• Same merge runs on island creation/reset/registration and ownership transfer (after the new owner's perms are applied).
• Coop and trusted players are not team members (Island.getMemberSet() is rank ≥ MEMBER) and never apply.

Documented caveat (in config comments): limits recalculate on login, so revoking a member's permission or kicking them takes effect at the owner's next login — consistent with how owner permissions already behave.

How

JoinListener.checkPerms is split into the clearing part and a new mergePerms (apply without clearing — the max-merge already existed in applyLimit). onPlayerJoin now also matches islands where the player is a qualifying member. The LimitsJoinPermCheckEvent fires for member joins too, so other plugins can cancel.

Tests

Five new JUnit cases: member ignored when disabled; member merged when enabled (and never clears); member perm doesn't lower a higher existing limit; owner join merges online members' perms after recalc; offline members ignored. Full suite: 261 tests green.

In-game test plan

1. Enable apply-member-limit-perms: true, set blocklimits: HOPPER: 10.
2. Owner (no perms) + member with bskyblock.island.limit.hopper.50: member logs in → /is limits shows 50 for both.
3. Owner relogs while member online → still 50. Owner relogs while member offline → back to 10 (documented caveat).
4. Give a coop player the same perm → no effect.
5. Transfer ownership to the member → limits recalculated from new owner's perms.
6. With the option left false (default) → member perms have no effect (current behaviour unchanged).

🤖 Generated with Claude Code

https://claude.ai/code/session_015dbJyrv2uxHfTmiWkqGUJB

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
90.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud