refactor: centralize todo status and priority enums

[salignatmoandal]

refactor: centralize todo status and priority enums

Description

This PR centralizes the Zod enums for todo status and priority into a single shared file (src/util/schemas.ts). The goal is to avoid duplication, improve maintainability, and ensure consistency across the codebase.

Changes

• Created src/util/schemas.ts to export:
• StatusEnum (pending, in_progress, completed)
• PriorityEnum (high, medium, low)
• (Optionally) a shared TodoInfo schema and types
• Updated src/tool/todo.ts to import and use these enums instead of local definitions.
• Updated TypeScript types to use z.infer<typeof StatusEnum> and z.infer<typeof PriorityEnum>.

Motivation

• Single source of truth for todo status and priority values.
• Easier future changes: adding or renaming a status/priority only requires editing one file.
• Consistency: all modules use the exact same validation and types.

Checklist

• [x] All usages of todo status and priority enums in src/tool/todo.ts now use the shared enums.
• [x] Types are inferred from Zod schemas.
• [x] All tests pass (bun test).
• [x] Code style and conventions follow the project’s AGENTS.md guidelines.

Notes

• This PR is limited to the todo tool. If similar enums are found elsewhere, a follow-up PR can further centralize them.
• Please let me know if you prefer the shared TodoInfo schema to be used in other modules as well.

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Thank you for reviewing!

[thdxr]

why?

[salignatmoandal]

why not?