Roll out ecosystem code-style policy: swift-format + SwiftLint + comment-ratio check

[gsdali]

What

Roll out the ecosystem's proposed code-style policy to this repo, following the pattern already
proven in OCCTSwiftScripts#114 /
#115 (the reference implementation
for a repo this size): a full sweep, not a gradual exemption manifest.

Proposal doc: ecosystem docs/code-style-policy-proposal-2026-08.md

Scope for this repo

• .swift-format (100 col, 4-space, copied verbatim from OCCTSwiftScripts) +
  .swiftlint.yml scoped to only_rules: [orphaned_doc_comment] (avoids fighting swift-format's
  own formatting opinions and the ecosystem's separate code-structure policy).
• Scripts/comment-ratio-check.sh: report-only nudge (never fails), bash to match
  OCCTSwiftScripts's own convention.
• A full sweep: swift-format format --in-place --recursive across Sources/ and Tests/
  (~4,989 lines, ~56 files across the layered OCCTSwiftUX/Resolver/Model/Kit/
  ViewportBridge/ViewportService targets), then hand-fix every remaining
  swift-format lint --strict / swiftlint lint --strict finding until both report zero.
• .github/workflows/code-style.yml: new blocking CI job (swift-format lint --strict +
  swiftlint lint --strict blocking, comment-ratio report-only). This repo has no
  .github/workflows/ today, so this bootstraps CI from nothing.
• okf/policies/code-style.md, linked from okf/index.md, the 7th policy in this repo's OKF
  bundle (alongside code-structure, context-first, docs-current, issue-tracking,
  search-before-building, writing-style).

Explicitly out of scope here

• clang-format — zero first-party C++ bridge files in this repo (confirmed).
• Any docs-drift tooling beyond the comment-ratio nudge — out of scope for this pass, matching
  OCCTSwiftScripts#114's own scoping.

Process

Filed per the ecosystem policy's own gate: no repo implements without a filed issue first. PR to
follow, referencing this issue. Holding for review before merge.