Fix Codex weekly window detection

[anthfgreco]

Fixes #267

Summary

• Identify Codex session and weekly usage windows from duration/reset metadata instead of array position.
• Preserve an absent 5-hour session as an informational unavailable lane.
• Calculate provider pace from the weekly quota when no session window is present.
• Mark the unavailable session consistently in the tray status, Settings usage section, and CLI output.

Root cause

Codex weekly-only payloads were promoted into the primary window, while array payloads assumed the first window was always the 5-hour session. That mislabeled weekly usage and left the weekly and pace lanes incorrect.

Validation

• cargo fmt --all
• git diff --check
• cargo test --manifest-path rust/Cargo.toml codex
• cargo test --manifest-path apps/desktop-tauri/src-tauri/Cargo.toml commands::bridge
• cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
• cargo clippy --manifest-path apps/desktop-tauri/src-tauri/Cargo.toml --all-targets -- -D warnings
• Frontend Vitest was unavailable because apps/desktop-tauri/node_modules is not installed.
• Cua proof was skipped per the requested config-only scope.

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[Finesssee]

Thanks for the PR, I will review it ASAP.