feat: Add OAuth scopes to tool metadata (Phase 1)

[SamMorrowDrums]

Summary

This PR adds OAuth scope metadata to all MCP tools, enabling clients to know which scopes are required for each tool before calling them.

Changes

New Package: pkg/scopes

• scopes.go: OAuth scope constants based on GitHub's OAuth app scopes documentation

  • Scope type with constants for all GitHub OAuth scopes (Repo, PublicRepo, Notifications, Gist, SecurityEvents, Project, ReadProject, ReadOrg, etc.)
  • ScopeHierarchy map defining parent-child relationships (e.g., repo includes public_repo, security_events, etc.)
  • WithScopes() helper to create mcp.Tool.Meta maps
  • GetScopesFromMeta() to extract scopes from tool metadata
  • ScopeIncludes(), HasRequiredScopes() for scope checking

• scopes_test.go: Comprehensive test coverage for all utilities

Tool Updates (~90 tools)

Added Meta: scopes.WithScopes(...) to all tool definitions:

Scope	Tools
repo	Most repository, issue, PR, actions, discussions, search tools
public_repo	star_repository, unstar_repository
notifications	All notification tools
gist	create_gist, update_gist
security_events	Code scanning, dependabot, secret scanning, security advisories
project	Project write operations
read:project	Project read operations
read:org	get_teams, get_team_members, list_issue_types
No scope	get_me, list_gists, get_gist (public reads)

Documentation Updates

• generate_docs.go: Updated to include scope information in README output
• README.md: Now shows (scopes: \repo`)` after each tool description
• Toolsnaps: All updated with _meta.requiredOAuthScopes array

Testing

• All existing tests pass
• New test file pkg/scopes/scopes_test.go with tests for:
  • TestScopeString - Scope string conversion
  • TestScopeIncludes - Hierarchy checking
  • TestHasRequiredScopes - Multiple scope validation
  • TestWithScopes - Meta map creation
  • TestGetScopesFromMeta - Meta extraction
  • TestGetAcceptedScopes - Parent scope lookup
  • TestScopeStringsAndParseScopes - Round-trip conversion

Part of OAuth Scopes Work (Phase 1 of 4)

• Phase 1 (this PR): Add OAuth scopes to tool metadata ✅
• Phase 2: Add fine-grained permissions to metadata
• Phase 3: Create script to list required scopes for enabled tools
• Phase 4: Export Go map for library usage