[amol-]

The documentation configuration fails to parse on Python 3, and the PDF target references a nonexistent root document. Restore the real build and add CI coverage against regressions.

Changes:

• Repair Sphinx configuration, current version metadata, source warnings, and navigation.
• Share documentation dependencies between CI and standard Read the Docs v2 configuration.
• Build strict HTML and an actual PDF in a separate CI job, inspect extracted content, and upload artifacts.
• Preserve the runtime test matrix and Python 3.8 support.

Validation at 500f50c:

• All 8 CI jobs passed: https://github.com/bbangert/beaker/actions/runs/40596340126
• Actual PDF compilation produced a readable 61-page manual. QA visually inspected sample pages and verified all 23 HTML pages for local targets, API content, navigation, and assets.
• Strict actual-configuration HTML/LaTeX builds and existing Makefile targets passed.
• Code-quality, bug-hunter, and QA reviews approved. The bug-hunter confirmed the reported PDF-build defect is fixed.

Read the Docs publishing remains externally blocked/unverified: the public site still serves a 2018 build. An authorized maintainer must inspect/reconnect the project integration, trigger the latest build, and verify deployed HTML/PDF after merge. This PR does not claim public deployment occurred.

Fixes #83