chore: slim post-4.3 repository

[BrannonSD]

Post-4.3.2 repository maintenance only.

• Removes the isolated abandoned marketing demo tree and obsolete phase/release drafts.
• Consolidates current distribution/update guidance into docs/DISTRIBUTION.md.
• Replaces historical compiler portability framing with docs/VERSE_COMPILER.md.
• Preserves the release acceptance report in BrannonSD/personal-tasks.
• Removes the proven-unused compile-audit helper.
• Leaves src/, electron/, server/, shared/, skills/, release workflows, updater behavior, and version 4.3.2 unchanged.

Local validation before push: npm ci; npm audit --omit=dev --audit-level=high; npm run test:all (275 JS, 19 Python, 7 portable-updater); npx tsc --noEmit; git diff --check.