feat(circle): add CircleCI scanner and improve debug progress logs

[frjcomp]

No description provided.

[Copilot]

Pull request overview

Adds CircleCI support to Pipeleek by introducing a new CircleCI scanner implementation, CLI commands, and corresponding configuration + test coverage.

Changes:

• Introduce a CircleCI scanning engine (pipelines → workflows → jobs) with optional test/insight/artifact scanning.
• Add pipeleek circle scan command (and a dedicated pipeleek-circle binary) plus Makefile targets.
• Add CircleCI configuration examples/docs and unit/e2e tests.

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tests/e2e/circle/scan/scan_test.go	New CircleCI e2e coverage using a recorded mock server.
pkg/circle/scan/transport.go	CircleCI API transport/client wrapper for v2 + selective v1 fallback endpoints.
pkg/circle/scan/transport_test.go	Unit tests for org discovery fallback + v1 discovery normalization/filtering.
pkg/circle/scan/scanner.go	Core CircleCI scanner orchestration + option initialization.
pkg/circle/scan/scanner_test.go	Unit tests for slug normalization and log flattening helpers.
pkg/circle/scan/normalize.go	Slug/VCS/org normalization and filter helpers for CircleCI.
internal/cmd/circle/scan/scan.go	Adds circle scan Cobra command and config binding.
internal/cmd/circle/scan/scan_test.go	Verifies Circle scan command wiring/flags.
internal/cmd/circle/circle.go	Adds CircleCI root command and registers scan subcommand.
internal/cmd/circle/circle_test.go	Verifies Circle root command structure.
internal/cmd/root.go	Registers CircleCI command group and root command.
cmd/pipeleek-circle/main.go	Adds dedicated CircleCI-only binary entrypoint.
pipeleek.example.yaml	Adds CircleCI configuration example stanza.
docs/introduction/configuration.md	Documents CircleCI configuration keys/flags.
Makefile	Adds build/test targets for CircleCI binary and e2e suite.
go.mod	Adds CircleCI client dependency (and resulting transitive updates).
go.sum	Updates checksums for new/updated dependencies.