Add Markdown output support to brief inspect #180

Summary

brief inspect supports JSON and human-readable output but does not support Markdown. This differs from the primary scan and the other reporting commands, which support --markdown for agent and CI-oriented output.

Markdown is also lost when an artifact passed to the primary command is automatically routed to inspect.

Current behavior

Explicit inspection rejects the flag:

brief inspect --markdown dist/package.whl

flag provided but not defined: -markdown

Automatic inspection accepts the primary command's flag but does not carry it into cmdInspect:

brief --markdown dist/package.whl

When stdout is not a terminal, this produces JSON rather than Markdown.

Root cause

• cmdInspect defines only --json and --human.
• The report package provides ArtifactJSON and ArtifactHuman, but no ArtifactMarkdown.
• inspectAutoArgs accepts and forwards only the JSON and human flags.

Expected behavior

Both forms should produce equivalent Markdown artifact reports:

brief inspect --markdown dist/package.whl
brief --markdown dist/package.whl

Proposed implementation

• Add a --markdown flag to cmdInspect.
• Implement report.ArtifactMarkdown(w io.Writer, art *brief.Artifact).
• Pass the Markdown flag through inspectAutoArgs when auto-routing from the primary command.
• Preserve the existing precedence in which Markdown wins when multiple output flags are supplied.

The Markdown report should include:

• Artifact path, container format, SHA-256, archive entry count, native object count and duration.
• A section for each native object with path, format, architecture, SOName, producers, required dynamic libraries, Go build information and static-library hints.
• Proper Markdown escaping for artifact paths and all metadata originating from inspected files.

Suggested tests

• Unit-test ArtifactMarkdown with an archive containing multiple native objects.
• Cover empty optional fields and an artifact with no native objects.
• Verify Markdown escaping for pipes, newlines and other table-sensitive content.
• Verify brief inspect --markdown artifact selects Markdown output.
• Verify brief --markdown artifact preserves Markdown through automatic inspection.