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.
• Allow admins to set the policy through POST /api/v1/orgs and change it through PUT /api/v1/orgs/:id, with validation and audit detail.
• Expose the policy as a constrained selector in both organization admin editors.
• Document that existing physical tables must be migrated before changing the policy for an organization that has already written data.
• Add migration, API, Postgres persistence, and admin UI coverage.

Important

Deploy this before PostHog/posthog#76032. Apply any deliberate policy exceptions after this migration and before the PostHog writers deploy.

Tests

• just test-controlplane
• just test-controlplane-k8s
• just test-configstore-integration
• just ui-test
• 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. The admin API and both admin interfaces provide a validated override for deliberate exceptions without direct database writes.

[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	4	0
E2E/journey files	0	0	0
Workflow files	0	0	0

Signals

• Test cases: +5 / -0
• Assertions: +27 / -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.