Synchronize main lineage into dev before the downloads release

[sjungwon03]

Problem

Release PR #165 was squash merged into main as 9a45159. A squash merge discards the parent relationship, so main and dev now share no ancestry for that work even though their content matches. Git therefore reads the same changes as independent edits on both sides, and the release PR #169 reports CONFLICTING / DIRTY.

Reported conflicts:

• apps/openscene/app/page.tsx
• apps/openscene/lib/docs/content.en.ts
• apps/openscene/lib/docs/content.ko.ts
• rename/rename on apps/openvideo/public/logo.svg and apps/theorvane/public/products/openvideo.svg, which the rename in feat: rename OpenVideo to OpenScene and move the site to openscene.app #160 and the product-landing work resolved to different destinations on each side

Scope

Graph repair only, following the pattern established by #132, #139, and #157.

• Branch release/<this issue>-sync-main-lineage from current origin/dev.
• Merge origin/main into it as a merge commit, taking dev content on every conflict — main has no content dev lacks, because main received it from dev via the squash.
• Prove the result is content-neutral: the candidate tree must equal the current origin/dev tree.

Acceptance criteria

• git diff origin/dev <candidate> is empty.
• Both origin/dev and origin/main are ancestors of the candidate.
• npm run lint, npm run typecheck, npm test, npm run build, npm audit --omit=dev --audit-level=high, and git diff --check pass.
• After the merge, Release: promote the OpenScene downloads to production #169 reports mergeable.

Non-goals

• Any content, runtime, workflow, or deployment change.
• Squash or rebase merge of the sync PR. Either would discard the main parent and leave the lineage unrepaired.