docs(glossary): refresh with new terms

[hkimw]

Summary

• Add the public glossary page from the q12 terminology scaffold.
• Refresh it with May 7 terms from the v002.1 spec, design-decision, quickstart, release-template, contributors, and news docs.
• Link the glossary from the root and docs indexes.

Tests

• git diff --check
• rg -n "KV260 inference works|Gemma 3N E4B runs on KV260|20 tok/s achieved|timing closed|bitstream ready|production-ready|stable release|achieved throughput|delivers|reaches|demonstrates" docs/glossary.md returned no matches
• PATH=/home/hwkim/Desktop/github/pccxai/pccx/.venv/bin:$PATH make strict SPHINXBUILD=/home/hwkim/Desktop/github/pccxai/pccx/.venv/bin/sphinx-build
• PATH=/home/hwkim/Desktop/github/pccxai/pccx/.venv/bin:$PATH make lint

Notes

• codes/v002 was cloned in the worktree as gitignored build input before running make strict.
• The strict build printed existing social-card font glyph UserWarnings while completing successfully.

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