RFC-18: update deployment automation for testnet/mainnet rollout

[ben-malbeclabs]

Deployment automation will need to be audited and updated to support the RFC-18 rollout described in #3360.

What needs to happen:

The RFC-18 rollout introduces a specific deployment sequence that differs from a standard binary upgrade:

1. Deploy updated onchain program
2. Create UNICAST-DEFAULT topology
3. Start activator with the new --enable-flex-algo flag
4. Run doublezero-admin migrate flex-algo to tag existing links and backfill loopback node segments
5. Start/restart controller (only safe after migration completes)

Existing deployment scripts and configuration management will need to be reviewed to determine whether they can accommodate this sequence, and updated accordingly.

Scope of work:

• Identify which parts of the deployment tooling are affected
• Update scripts/configuration to reflect the new activator flag and the ordered deployment sequence
• Ensure the migration step is represented as a distinct, manual checkpoint (not automated alongside the binary rollout)

Dependencies: #3360 (testnet rollout sign-off) must be completed first.

[ben-malbeclabs]

Partially outdated: the activator has been removed (#3607), so steps referencing activator deployment and --enable-flex-algo flag are no longer relevant. The remaining scope is:

• Ensure release.devnet.all.daily (and testnet/mainnet equivalents) deploy the controller with the correct features.yaml from the infra branch
• Ensure the daily provisioning test preserves flex-algo state (fixed in PRs e2e/qa: use dedicated restart playbooks for provisioning test #3641, Activator ignores SIGTERM/SIGINT and never exits #1215, Add Record program SDK #1217, e2e/qa: poll for device pubkey before running Ansible restart #3646)
• Ensure CreateDeviceInterface assigns node segments automatically (fixed in PR smartcontract,controller: RFC-18 devnet fixes — node segment assignment and community stamping #3648)