[codex] Use projectRequirements in project requirement queries

[welias]

What changed

• switched project requirement reads from project.playbooks/activity.playbook to project.projectRequirements
• updated projects requirements, requirements project, and requirements activities --project-id to read project-forked requirements and activities
• updated tasks list and tasks run to load project requirement activities from projectRequirements.activities
• adjusted README wording to reflect project requirements instead of playbooks

Why

The API changed after requirements started being forked per project. playbook is now just the template reference, while the source of truth for project data is projectRequirements. The CLI was still querying the old path, which caused missing or broken activity listings for project-scoped requirement commands.

Impact

• project-scoped requirement listings now return the project requirement ids
• project-scoped activity listings include forked activities correctly
• task discovery/execution now reads the project-forked activities instead of template checks
• requirements project and requirements activities --project-id also expose the template reference via templateRequirementId and templateRequirementLabel

Root cause

The CLI still assumed pre-fork API semantics and queried template-backed fields for project data.

Validation

• PYTHONPATH=src ./.venv/bin/python -m py_compile src/conviso/commands/projects.py src/conviso/commands/requirements.py src/conviso/commands/tasks.py
• PYTHONPATH=src ./.venv/bin/python -m conviso.app projects requirements --project-id 23662 --format json
• PYTHONPATH=src ./.venv/bin/python -m conviso.app requirements project --company-id 1 --project-id 23662 --with-activities --format json
• PYTHONPATH=src ./.venv/bin/python -m conviso.app requirements activities --company-id 1 --project-id 23662 --format json
• PYTHONPATH=src ./.venv/bin/python -m conviso.app tasks list --company-id 1 --project-id 23662 --format json