Rebrand: pinpt/esp → AbsolutOD/esp + LICENSE/README refresh

[AbsolutOD]

Summary

• Rename Go module path from `github.com/pinpt/esp` to `github.com/AbsolutOD/esp` (1 module declaration + 17 import statements across 12 files).
• Prepend `Copyright 2021-2026 Matt O'Donnell` to `LICENSE` (Apache 2.0 terms unchanged).
• Strip the unfilled Cobra-scaffold copyright comment block from `main.go`.
• Delete the legacy Pinpoint logo (`.github/logo.svg`).
• Full `README.md` rewrite covering install, configuration, `.espFile` format, command summary, common workflows, and logging.
• One small follow-up: update the post-rebrand module path in the cleanup-and-tests spec doc.

No Go code logic changes. No CI changes. No license change.

Test Plan

• `go build ./...` exits 0
• `go vet ./...` exits 0
• `go test ./...` passes (`cmd`, `internal/app`)
• `./esp --help` prints usage without AWS env vars set
• Spot-check the rendered README on GitHub for table/markdown rendering
• Confirm `LICENSE` first line reads `Copyright 2021-2026 Matt O'Donnell`

Spec: `docs/superpowers/specs/2026-05-05-rebrand-design.md`
Plan: `docs/superpowers/plans/2026-05-05-rebrand.md`