fix(tasks): enforce authenticated task mutations [NSoC'26]

[saurabhhhcodes]

Summary

• remove duplicate unauthenticated task mutation route registrations
• require authenticated users for task listing and task creation
• persist owner_id on created tasks and scope task status/edit/delete mutations to the authenticated owner
• preserve the existing project_id payload used by the Kanban frontend

Closes #152

Validation

• node --check backend/controllers/tasks.controller.js
• node --check backend/routes/tasks.routes.js
• node --check backend/server.js
• git diff --check

Notes

• The backend package currently does not define a test script, so validation is syntax and diff hygiene focused.
• Ownership is enforced using the existing owner_id convention already used for owned resources in this repo Supabase project routes.

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Project	Deployment	Actions	Updated (UTC)
flow-forge	Ready	Preview, Comment	Jun 5, 2026 2:18pm

[Shriii19]

@saurabhhhcodes having the conflict pls fix it.