chore(backend): rename openfootmanager_lib crate

[NicoRuedaA]

Problem or opportunity

src-tauri/Cargo.toml defines the lib crate as name = "openfootmanager_lib". This is the old football project name and should be updated to match the LoL rebrand.

Proposed solution

Rename crate to "openleaguemanager_lib" in Cargo.toml and update all references in the workspace (Cargo.lock, other crates that depend on it, Tauri config).

UX impact

None — build artifact names change slightly.

Acceptance criteria

• Crate renamed in src-tauri/Cargo.toml
• All workspace references updated
• Tauri build succeeds
• No broken imports

Scope

CI / release

[NicoRuedaA]

PR: #65