feat: add lazy paging with generated PagedEnumerable methods

[glennawatson]

Summary

A Refit method can return PagedEnumerable<TPage, TItem>, and the source generator writes the paging loop.

• PagedEnumerable<TPage, TItem> reads a paged list lazily with await foreach. It wraps a Refit method that returns one page, yields the items or the API's own page objects, and sends a fresh request per page.
• [Paged] and [PageToken] make the generator emit the loop. [Paged] names the item and continuation members of the page, and [PageToken] marks the parameter that carries the token.
• Cursors, offsets, response headers and next links are supported. Member names are resolved to direct property access at build time, so a misspelled name is a build error.
• A method that follows links must state which origins a link may point at. Origins, SameOrigin or AnyOrigin decides it, and a refused link is never requested.
• Enumeration supports early stop, WithMaxPages, WithPrefetch, cancellation of the request in flight, and observable forms. Each page is disposed as the consumer moves on.
• IApiResponse.GetLink reads Link response headers.
• An empty string cursor ends a cursor sequence.
• A misconfigured paged method reports RF013.
• Runnable examples mock S3, Azure Blob Storage, Cosmos DB, Microsoft Graph, GitHub, Google Cloud Storage, Jira and DynamoDB.
• The Visual Studio Threading analyzers package and its inline suppressions are removed.
• docs/breaking-changes.md gains the V16 and V15 sections.
• CLAUDE.md describes paging and the public API baseline workflow.

Why

Every list API that returns pages makes callers hand-write the same request loop, and each service names the next page differently: S3 and Google Cloud Storage use a token in the body, Cosmos DB a header, Graph and GitHub a link, Jira an offset. There is no linked issue.

Breaking changes

None. The public API baselines only gain lines.

How this was verified

Tests cover every type this adds, the generator output and its diagnostics, and generated clients paging against a fake server. The example project runs every service scenario against local stand-ins.

Notes for the reviewer

• Start with Parser.Paging.cs and Emitter.Inline.Paged.cs. The parser resolves the attribute members against the page type. The emitter writes a sibling request-building member plus the method that hands it to PagedEnumerable, so each page rebuilds its request.
• Mechanical parts: the PublicAPI baselines, the generator snapshots, and the example DTOs and mocks.
• Out of scope: the reflection request builder rejects paged returns, and the generator reports RF007 when a paged method cannot be generated inline.
• The documentation page is in docs(refit): add the pagination page website#996.

Checklist

• I have read the Contribute guide
• The PR title follows Conventional Commits
• Tests cover this change, or the summary says why they do not
• New or changed public API has XML documentation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5106e9c) to head (3443af1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##              main     #2332    +/-   ##
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  Coverage   100.00%   100.00%            
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  Files          194       206    +12     
  Lines        10138     10805   +667     
  Branches      1947      2106   +159     
==========================================
+ Hits         10138     10805   +667     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud