[ci skip] Flatten module wrappers into stack roots

Remove the module "xxx" { source = "./module" } indirection layer
from all 66 service stacks. Resources are now defined directly in
each stack's main.tf instead of through a wrapper module.

- Merge module/main.tf contents into stack main.tf
- Apply variable replacements (var.tier -> local.tiers.X, renamed vars)
- Fix shared module paths (one fewer ../ at each level)
- Move extra files/dirs (factory/, chart_values, subdirs) to stack root
- Update state files to strip module.<name>. prefix
- Update CLAUDE.md to reflect flat structure

Verified: terragrunt plan shows 0 add, 0 destroy across all stacks.

stacks/ytdlp/module/yt-highlights/requirements.txt

@@ -1,10 +0,0 @@
-fastapi>=0.104.0
-uvicorn>=0.24.0
-yt-dlp==2025.12.8
-faster-whisper>=1.0.0
-httpx>=0.25.0
-requests>=2.31.0
-pydantic>=2.0.0
-python-multipart>=0.0.6
-feedparser>=6.0.0
-redis>=5.0.0