[Rosetta-0] Audit and freeze current docs and matrix #864

Goal

Record exact docs debt. Freeze baseline so later diffs stay reviewable.

Tasks

• List all files under docs/ with line counts and status: active, stub, stale.
• Record empty headings in docs/README.md: section 6 API, 5.3.1.1-5.3.1.7, 5.3.2.1-5.3.2.2, 5.3.3.1, 5.5 Serialization, 5.6 Memory Layout.
• Record TOC bug: 4.2 and 4.3 nested under 4.1 though headings are level 3 siblings.
• Record branch mix: docs/README.md uses master image links, README.md uses develop.
• Record broken ref: .github/PULL_REQUEST_TEMPLATE.md links to docs/README.md#63-debugging, actual section is 7.3.
• Inventory loaders: 21 wired in source/loaders/CMakeLists.txt plus orphans source/loaders/deno_loader/ and source/loaders/kind_loader/ with no CMake entry.
• Inventory ports: 15 wired in source/ports/CMakeLists.txt, plus nim_port/ and scala_port/ unwired. Note anomaly: OPTION_BUILD_PORTS_TS exists but source/ports/ts_port/ dir is absent.
• Inventory tests: ~175 targets in source/tests/CMakeLists.txt (verify exact active count), list disabled suites and linked issue IDs.
• Check .github/workflows/ coverage: linux, windows, macos, freebsd, haiku, android-test, benchmark, clang-format, docker-hub, release.
• Publish audit table in this issue. Lock scope for Rosetta-1 to Rosetta-8.

Acceptance

• Audit table posted with file paths and counts.
• Orphan and disabled lists confirmed by maintainer.
• No docs edits in this issue except audit report.