RESULT: SUCCESS

FILES CHANGED:
- internal/toml/decode.go
- internal/toml/value_test.go

SUMMARY:
Implemented robust bare, quoted, and dotted key parsing; nested arrays; comments; mixed values; trailing commas; and malformed-input rejection. Added focused Go tests.

Validation passed:

- Key valid: 28/28
- Key invalid: 61/61
- Array valid: 21/21
- Array invalid: 26/26
- `go test -race ./...`
- `go vet ./...`

BLOCKERS:
- Full conformance still has unrelated failures in table lifecycle, floats, inline tables, integers, and strings outside this build block.