feat(control-plane): version data import table naming

[EDsCODE]

Problem

Existing organizations need to keep the data-import table names they already use, while newly provisioned organizations should use the copy workflow naming format. The naming choice must be stable at organization scope and available to PostHog writers.

Changes

• Add an organization-level data_imports_table_naming_version with legacy_batch_v1 and copy_v1 values.
• Backfill existing organizations to legacy_batch_v1, then make copy_v1 the database default for organizations created after the migration.
• Return the organization policy from GET /api/v1/orgs/:id/teams alongside the team rows.
• Add migration coverage for fresh databases, upgrades, and the existing-versus-new default boundary.

Important

Deploy this before PostHog/posthog#76032. Any deliberate exceptions should be applied as operator-managed organization configuration after this migration and before the PostHog writers deploy.

Tests

• just test-controlplane
• just test-configstore-integration
• just lint

Agent context

Codex implemented this as a human-directed change. The migration intentionally separates the backfill value from the post-migration default so existing and newly provisioned organizations take different policies without hard-coded tenant data.

[github-actions]

Test Impact Plan

Deterministic summary of how this PR changes tests, CI runners, and coverage-risk signals.

Summary

Area	Added	Changed	Deleted
Test files	0	2	0
E2E/journey files	0	0	0
Workflow files	0	0	0

Signals

• Test cases: +1 / -0
• Assertions: +11 / -0
• Skips or known failures added: 0
• Workflow continue-on-error added: 0
• Workflow path filters added: 0
• Test commands removed from justfile: 0
• E2E/journey retry lines added: 0

Coverage risk: neutral or increased

No coverage-reduction warnings detected.