docs(glossary): phase 5 generated glossary parity

[PLeVasseur]

Summary

• Generate glossary content from chapter definitions and enforce parity checks.
• Add deterministic generation and CI-equivalent parity guardrails.

Reference alignment

• Follow-up to glossary: generated-only glossary source with reproducibility checks rust-lang/fls#656 and Tshepang phased strategy (step 5/5).
• No glossary-entry/glossary-include directives are introduced.

Testing

• ./make.py --clear
• ./make.py --check-links
• uv run ./tools/glossary-migration-check.py --phase 5 --strict --report "$REPORT_ROOT/glossary-phase5-check.json"
• ./generate-glossary.py && diff -u build/generated.glossary.rst src/glossary.rst.inc

[PLeVasseur]

Restack update: this branch was synchronized after PR6/PR7 remediation and downstream PR8/PR9 restacks.

• Branch glossary-step-5-generated-glossary-parity was merge-restacked from glossary-step-4-remove-see-paragraphs at 8e8b08b.
• Generated include parity was refreshed post-restack in 7444888.
• Please refresh review context because inherited commits and base ancestry changed.