Part 3 - Tool NRPS: typed endpoints, pagination, filters, and structured errors

[eliknebel]

This PR adds full tool-side NRPS support on top of the core and deep-linking work. It introduces typed NRPS endpoint
parsing, scope enforcement, pagination traversal, filter normalization, structured errors, telemetry, and both
streaming and eager roster retrieval APIs.

This PR should be reviewed and landed after #43

What Changed

• Added NRPS public APIs:
  • Lti_1p3.Tool.Services.NRPS.from_launch_claim/1
  • Lti_1p3.Tool.Services.NRPS.list_memberships/3
  • Lti_1p3.Tool.Services.NRPS.stream_memberships/3
  • Lti_1p3.Tool.Services.NRPS.fetch_all_memberships/3
• Refactored legacy fetch_memberships/2 through the stricter NRPS pipeline while preserving its legacy tuple shape
• Added NRPS support modules for:
  • endpoint typing
  • parser
  • client
  • membership page model
  • scope policy
  • structured errors
  • telemetry
• Added shared HTTP helpers for reuse across services:
  • Lti_1p3.Services.HTTP.LinkHeader
  • Lti_1p3.Services.HTTP.QueryFilters
• Added NRPS guide, QA report, utility extraction notes, and requirement matrix docs
• Added CI coverage for the new HTTP helper tests

Why

The previous implementation was single-page oriented and too loose around scopes, filters, and failure semantics. This
PR makes NRPS usable for production roster retrieval and establishes shared HTTP utilities needed by later service
work.

Reviewer Notes

Focus review on:

• Link header traversal
• filter normalization and encoding
• scope enforcement
• retry/error metadata
• API compatibility for fetch_memberships/2

Most of the cumulative diff is inherited from PRs 1 and 2. The incremental review surface is the NRPS modules plus the
shared HTTP paging/filter helpers.

Documentation

• docs/tool_nrps_guide.md
• docs/features/tool-nrps/*
• README.md
• CHANGELOG.md