Wire profile/module resolution into the actual install flow. Manifests and plan resolver exist, execution is the missing step.

Scope:

• ecc-install --profile <name> and --modules <id,...>
• Target-aware filtering
• Legacy language install compat during rollout
• Tests for profile resolution and installer behavior

Foundation already landed: manifests/install-modules.json, manifests/install-profiles.json, scripts/install-plan.js, scripts/lib/install-manifests.js

GitHub #423