M5.5: Implement terminal table renderer

[bjcorder]

Labels: type:feature, area:report, priority:normal,
status:blocked, milestone:M5, phase:9

Summary

Render scan results as a clean terminal table for human consumption.

Acceptance criteria

• internal/report/table.go exposes:
  • func RenderTable(w io.Writer, scan Scan, findings []Finding) error
• Uses github.com/jedib0t/go-pretty/v6/table
• Columns: Advisory, Severity, Status, Summary, Fix Commits
• Color-codes status: red for VULNERABLE, green for PATCHED_*, etc.
• Truncates summary to fit terminal width

Dependencies

Depends on: #20

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