Declutter repo root (scripts/docs/configs)

[borisolver]

Implements the high-ROI part of Gemini's 10/10 guidance: remove root-level noise and make the Makefile the primary entrypoint.

Changes:

• Move legacy one-off scripts into scripts/legacy/.
• Move local compose configs into conf/compose/.
• Move nginx configs into conf/nginx/.
• Move internal notes into docs/internal/ and migration docs into docs/migrations/.
• Add Makefile targets for local report-auth stack (make report-auth-up, make report-auth-down, make report-auth-logs, make report-auth-test).

Notes:

• Local *.env files remain git-ignored; for convenience they can live under conf/env/ (see conf/env/README.md).