Migrate all alekspetrov/pilot references to qf-studio/pilot

[alekspetrov]

Context

Repo migrated from alekspetrov/pilot to qf-studio/pilot. Docs and README are fixed, but 247 files in the Go source code still reference the old org.

Scope

Replace all occurrences of github.com/alekspetrov/pilot with github.com/qf-studio/pilot across:

• Go source files (internal/, cmd/, cloud/, desktop/, e2e/, stress/)
• Test files
• CLAUDE.md
• CONTRIBUTING.md
• .agent/ task/draft files
• Helm chart (deploy/helm/)
• Any other non-docs files

Also check for anthropics/pilot — should be zero but verify.

Notes

• Go module path in go.mod may need updating — check if it's already qf-studio/pilot or still alekspetrov/pilot. If changing go.mod, all import paths in every Go file need updating too.
• Run go build ./... and go test ./... after changes to verify nothing breaks.
• Docs (docs/) are already fixed — skip those.

Acceptance

• grep -r 'alekspetrov/pilot' . --include='*.go' --include='*.md' --include='*.yaml' --include='*.yml' | grep -v docs/ | grep -v node_modules returns zero results
• go build ./... passes
• go test ./... passes