Release spotpdf 0.8.0

[Hyperrick]

Release spotpdf 0.8.0

Publish the optional --report HTML diagnostics feature to PyPI and bind all stable installation examples, tag-bound project-content URLs, and release surfaces to 0.8.0.

• Move the diagnostic-report release notes from Unreleased to a dated [0.8.0] section and add the changelog comparison link.
• Bump pyproject.toml and refresh uv.lock to 0.8.0.
• Rebind every tag-bound github.com and github.com/ghraw README URL to v0.8.0, including the commit-pinned diagnostic-report guide, example instructions, and report screenshots from Add visual PDF diagnostic reports #42.
• Update the three stable install pins to spotpdf==0.8.0, the stable-release prose (now including the HTML diagnostic reports), the example spotpdf_version values, and both issue-template placeholders.
• Regenerate docs/images/generation.json and docs/report-example/capture.json provenance for the new source hashes.

All local gates from docs/releasing.md pass: metadata, notes, repository hygiene, docs-image check, ruff, size limits, the full unittest suite, the 9-run inventory benchmark, the public prepress corpus, dist build, PyPI README rendering, twine, distribution checks, smoke installs, and prepare-assets.