Harden export pipelines for 0.13.0-beta.2

[MiLattanzio]

Summary

• enforce cumulative pre-growth page, node/DOM, file and byte budgets across HTML, structured and standalone-page PDF exports
• expose the limits through the CLI and apply browser-specific memory, ZIP and object-URL lifetime controls in the WebAssembly playground
• add adversarial naming/resource tests, concurrent deterministic conversions and performance/allocation baselines
• harden NuGet/package/source gates with clean net8.0/net10.0 consumers, packaged CLI negative smokes, embedded PDB and exact-commit Source Link verification
• version and document the library and dotnet tool as 0.13.0-beta.2

Verification

• Release solution build: 0 warnings, 0 errors
• NUnitLite: 335/335
• extracted source archive: build + managed-only + 335/335
• library and CLI package audits: passed
• clean package consumers: net8.0 and net10.0
• packaged dotnet tool install/conversion/limit smokes: passed

Tracks #32.

[MiLattanzio]

CI follow-up: the first run correctly passed build/test, package/source archive and all six NuGet consumers, but all three packaged CLI consumers ended with status 1 after their expected negative limit checks.

Root cause: PowerShell retained the last expected native LASTEXITCODE=1 after the assertions had succeeded, so GitHub marked the step failed even though all three limit checks behaved correctly.

Fix pushed in bb41ee0: reset the automatic exit code only after all negative assertions pass. The exact packaged-tool smoke now ends with LASTEXITCODE=0 locally.

[MiLattanzio]

Final qualification is green on run 31965241607:

• build/test: Ubuntu, Windows, macOS
• NuGet pack + extracted-source archive
• clean package consumers: net8.0/net10.0 on all three OSes
• packaged CLI consumers: all three OSes

PR is clean and mergeable at head bb41ee0b9f86578a83c7c64257346c51aaa28586. Proceeding with merge.