chore: drop CF→AWS migration tooling and stale JS-port references

The CF→AWS data migration (closed 2026-05-16) is long done and the
tooling isn't wired into any production path. Remove the one-shot binary,
its support package, and the migration runbook.

In live code, replace 'JS-parity' / 'same shape as JS' / 'cross-runtime
KV migration' comments with the real, stable reason for each behavior
(wire-format invariant, null-vs-zero distinction, CloudWatch alarm field
name, etc.). 24 files touched across lolschedule, loldle, wordle, twentyq,
trading, misc, util, server, metrics, ai, keylock.

- delete cmd/migrate_cf_data/
- delete internal/migration/
- delete docs/cf-to-aws-migration-runbook.md

internal/modules/loldle/render.go

@@ -63,8 +63,8 @@ func buildRows(championName string, results []AttributeRow) []guessRow {
 }
 
 // formatRowGroups joins one or more guess-row groups into a single <pre>
-// block. Label column width is the max label across ALL groups, so stacked
-// guesses on a board align with each other (JS parity).
+// block. Label column width is the max label across ALL groups so stacked
+// guesses on a board align with each other.
 func formatRowGroups(groups [][]guessRow) string {
 	width := 0
 	for _, g := range groups {