Add doc comments to connection types and protocol enums

[martinjms]

Targets: epic/test-doc-pass
Depends on: #98
Epic: #95

[martinjms]

⚠️ [Worker Stuck] No PR after 30m. Re-dispatching (attempt 1 of 2).

[martinjms]

Opened PR #102 on branch feat/issue-99-add-doc-comments-to-connection-types-and (base: epic/test-doc-pass). Added doc comments to all remaining public types in arcane-core: server_pool.rs (connection types + protocol enums), cluster_simulation.rs, world_simulator.rs, and types.rs. Tests pass, format clean. Ready for review.