fix(codex): sync active profile provider after switch

[zhushihao]

Summary

After a device-level provider switch, the active project profile can retain the old provider and shadow Codex route ownership. This keeps the active profile provider slot aligned with the newly selected provider.

Changes

• Update the active project provider snapshot after a successful provider switch.
• Preserve existing MCP, Skills, and Prompt snapshots.
• Add regression coverage for profile and provider synchronization.

Validation

• Fork merge validation passed TypeScript, Prettier, and 148/1208 Vitest checks.
• Upstream CI will run Rust formatting, Clippy, tests, and frontend checks.

Risk

• Scoped to profile provider slots; non-provider project snapshots are left unchanged.