Purge abandoned legacy provider/surface dead code

[chubes4]

Completes an unfinished tech-debt purge that was staged in the primary checkout but never shipped (rescue stash "unshipped staged purge residue from primary (36 files, -2013 lines) 20260712"). Evaluated each deletion against current origin/main and kept only the still-valid dead-code removal.

Removed legacy debt

• Provider/runtime report summary (tests/smoke-provider-runtime-report-summary.php deleted, ~310 lines from report diagnostics). The provider-materialized vs runtime-gap rows were an extra abstraction layer; the underlying form/product seeding reports already surface the same facts.
• Static merch-card product extraction in the transformer adapter. The broad "*-card" XPath heuristic pulled in runtime commerce controls as fake products; bundle-data and JSON manifest paths remain the supported product sources.
• Navigation-list promotion, query-grid, and button-group heuristics in the safe-HTML fallback reducer. These were narrow, fixture-shaped transforms that produced brittle core/navigation, core/query, and core/buttons blocks. The reducer now falls back to bounded core/html for unsupported children.
• Provider-materializable classification in the Gutenberg incompatibility registry and JSON schema. Removed the Jetpack/Woo provider-evidence axis; gaps now classify as real Gutenberg gaps, transformer gaps, or runtime islands.
• Surface evidence aggregation in fixture-matrix intake/result/visual report. Per-surface artifact rows and summary counts are gone; fixture-level evidence remains.
• Import-report-based secondary surface editor target resolution and the shared editor-step target builder. Secondary surfaces now resolve to their candidate URL directly.
• Form label-text extraction helpers in report diagnostics.

Live features intentionally preserved

• Template-part shell deduplication and chrome stripping in page materialization.
• Runtime-control detection so cart/qty buttons are not faked as core blocks.
• Fallback markup preservation for unsupported children inside otherwise native containers.
• aria-hidden SVG skipping in inline HTML.
• Lab routing / shared-state / artifact-root behavior in run-fixture-matrix.

Verification

• npm test: 150 fixture-matrix tests pass, 3 fig-fixture-e2e tests pass.
• All tests/smoke-*.php pass.
• PHP syntax lint clean across all non-vendor PHP files.

AI assistance

• AI assistance: Yes
• Tool(s): Claude Opus 4.5 via OpenCode (orchestrator), Kimi K2.7 Code via OpenCode (implementation)
• Used for: Recovered and completed an abandoned legacy-code purge as a reviewed change