e2e compare: setClassMetadata extraction regex never matches (ɵɵ vs ɵ) — classMetadataDiffs is dead code #561

The e2e compare harness never actually compares setClassMetadata: extractClassMetadataCalls (src/compare.ts:2328) matches i\d+\.ɵɵsetClassMetadata but both compilers emit i0.ɵsetClassMetadata (single ɵ), so classMetadataDiffs is always empty and testFixture's known-difference gate never sees them.

Correcting the regex surfaces 79 fixture mismatches. Sampling shows most are normalization noise — same decorator payloads differing in quote style, indentation and trailing commas — so normalizeMetadataString needs to be made syntax-insensitive (e.g. parse and compare the AST or normalize quotes/commas) before the check can be enabled.

Steps: fix the regex, strengthen normalizeMetadataString, triage the residual diffs (real emit bugs vs. remaining noise), and extend KnownDifference to allowlist classMetadataDiffs per fixture — the new edge-cases/aliased-injectable entry should then declare its extra setClassMetadata explicitly.

Surfaced by a Codex review comment on #560.