fix: set event_deduplication in seed script

[kanishka0411]

Description

Seed script wasn't setting event_deduplication. Added a helper to compute it the same way upsert() does[pubkey, kind]for replaceable events, d tag values for parameterized replaceable ones.
event_delegator is no longer handled since it was removed in migration 20240111204900.

Fixes #135

Motivation and Context

Seeded events should match the same state as events inserted through the relay at runtime. Without event_deduplication, the unique index on replaceable events doesn't work correctly for seeded data.

How Has This Been Tested?

• Verified the deduplication logic matches EventRepository.upsert() and ParameterizedReplaceableEventStrategy
• Confirmed no duplicate dedup keys among seed data

Types of changes

• Non-functional change (docs, style, minor refactor)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my code changes.
• All new and existing tests passed.

[cameri]

Thank you @kanishka0411 !