feat(cli): Add reports command group for checkup reports

Summary

Add postgresai reports CLI commands and MCP tools for working with checkup reports.

CLI Commands

• postgresai reports list — list checkup reports with filtering by project, status, pagination
• postgresai reports files <reportId> — list files in a report (metadata)
• postgresai reports data <reportId> — get report file content (markdown/json)

MCP Tools

• list_reports — list reports with keyset pagination
• list_report_files — list report files by report ID or check ID
• get_report_data — fetch report content

Options

• --project-id, --status, --limit, --before (keyset pagination), --all
• --type (json/md), --check-id (e.g. H002)
• --output <dir> / -o — save files to directory
• --formatted — ANSI rendering for markdown
• --json, --debug

MR

!211 (merged)

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Acceptance Criteria

• postgresai reports list command lists checkup reports with filtering by --project-id, --status, and pagination (--limit, --before)
• postgresai reports files <reportId> command lists file metadata for a given report
• postgresai reports data <reportId> command retrieves report file content (markdown/JSON)
• MCP tools list_reports, list_report_files, and get_report_data are registered and functional
• --output <dir> flag saves report files to the specified directory
• --formatted flag renders markdown with ANSI formatting in the terminal
• --json and --debug flags work consistently with existing command patterns
• --type filter correctly separates JSON and markdown report files
• --check-id filter (e.g., H002) returns only the specified check's data
• --all flag retrieves all reports using automatic keyset pagination

Definition of Done

• MR !211 (merged) merged and released in a new CLI version
• Commands documented in CLI help text (postgresai reports --help)
• MCP tools discoverable and functional in AI assistant integrations
• All new commands follow existing CLI output formatting conventions