Emit map_migrated_tag_value in aws-wif placement output [murmur:back/bedrock-map-tagging]

[chenruichou]

Summary

Add an optional map_migrated_tag_value variable to the aws-wif module that, when non-empty, emits the value in the placement output's aws block as map_migrated_tag_value. The Go provisioner in murmuration reads this field and stamps map-migrated=<value> on every EC2 resource the placement creates.

Why

The dog-food placements (customer-prasso-tenant-vm-prod-aws account 684651436812, and nonprod-cstmr-plcmt-aws) are under Prasso's payer (231006511396) and their VMs should earn MAP credits. This field is the explicit own-account condition — set by whoever configures the placement, not derived from platform (which is false for the dog-food accounts). Without it, the dog-food VMs go untagged because the provisioner only stamps the tag when the placement carries a non-empty value.

Sequencing — this PR must merge FIRST

murmuration#6978 and back#15008 implement the rest of the MAP tagging. Both reference this module's new variable in TODO(MAP) comments. After this PR merges:

1. A follow-up murmuration PR bumps both aws-wif module refs (prod main.tf and nonprod nonprod-cstmr-plcmt.tf) to the resulting main-branch commit
2. Passes map_migrated_tag_value = "mig2R6T017255" on both dog-food modules
3. Applies and re-posts both placements

Backward compatible

The variable defaults to "". Existing callers that don't set it see no change — the placement output omits the field entirely.

Created via Murmur

🤖 Generated with Claude Code

[macroscopeapp-nonprod]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This change adds an optional AWS placement value that controls MAP cost-allocation tagging and can affect credits associated with EC2 spend. Because it may change financial outcomes when configured, it should receive human review.

^{You can add or adjust custom eligibility rules. Learn more.}