fix: ponytail audit — remove ~330 lines of redundant code

[locus313]

Summary

Third-pass complexity reduction across the codebase (~330 lines removed net).

Changes

lib/github-common.sh

• Add err() helper (print_error + exit 1 in one call)
• Add --api-version VERSION optional param to gh_api()

github-close-archived-repo-security-alerts

• Collapse 3 near-identical close_*_alerts() functions (~165 lines) into 1 generic close_alerts() (~55 lines)
• Replace 27-line hand-rolled archived-repo pagination loop with mapfile + gh_api_paginate

github-copilot-report

• Collapse _copilot_api() from 30 lines to 3 using --api-version 2026-03-10
• Remove info()/warn() pass-through aliases; replace call sites with print_status/print_warning
• Remove err() (now from lib)

github-repo-permissions-report

• Remove info() pass-through alias
• Remove err() (now from lib)

github-dockerfile-discovery

• Delete dead gh_api_link() function + RESPONSE_LINK global (~40 lines, never called)
• Remove vestigial print_* stderr-redirect redefines
• Inline check_prerequisites()

github-get-public-repos

• Inline check_prerequisites()
• Drop no-op print_error override (lib already writes to stderr)

7 pagination scripts (add-repo-permissions, add-repo-collaborators-by-pattern, archive-old-repos, enable-issues, get-repo-list, migrate-internal-repos-to-private, monthly-issues-report)

• Remove local get_repo_pagination()/limit_repo_pagination() wrappers; use get_repo_page_count from lib directly

github-organize-stars

• Replace 7-line hand-rolled command -v loop with require_command jq

github-archive-old-repos

• Inline validate_environment() into main()
• Move 14 pre-declared bare local vars to assignment site
• Drop stale/obvious comments

github-auto-repo-creation

• Merge add_teams_to_repo + add_repo_owners_to_repo into single add_team_to_repo repo team permission
• Remove obvious function-header comments and redundant variable comments

Docs

• AGENTS.md + copilot-instructions.md: add err() to helpers table, document --api-version on gh_api
• copilot-instructions.md: fix stale pagination example (was showing deleted get_repo_pagination() pattern); fill previously blank Shared Library section