style: establish governed C++ baseline

[imakris]

Implements the staged Batch 1B formatting baseline and the narrowly governed Batch 1C non-behavioral style-gate repairs.

Candidate: vnm_plot@2ec8013

Gates:

• canonical Varinomics no-write style pipeline: green (all 27 rule groups)
• repaired pipeline --write: green with zero file changes
• initialized MSVC Release build: green
• CTest: 21/21 green
• git diff --check: green
• PR CI: all eight QRhi/QRhi+Text jobs green on Linux, Windows, macOS, and FreeBSD

Review:

• iterative worker scope review: GREEN
• iterative worker tool review: GREEN after standards repair
• iterative worker full-diff review: GREEN
• Claude Fable independent full 24-patch review: GREEN

Dependency:

• Varinomics standards repair: fix: apply only confirmed style rewrites Varinomics/varinomics-standards#4 (ce01c3a)
• governance/implementation plan: Document stacking architecture and implementation plan #16 (dd5a14d)

Recorded non-blocking Fable follow-ups:

• improve checker coverage for enum-base spacing and isolated brace/call/initializer cosmetic artifacts
• optionally add direct revision-field cases for layout_cache_key_t::operator==

No material behavior, API/ABI, std140 layout, string-byte, or short-circuit issue was found.