test: Add 34 base 2023-09 conformance fixtures, strengthen 6

[leongdl]

Summary

34 new base 2023-09 fixtures plus 6 strengthened, from a systematic coverage audit of the base spec. Full suite goes 655 → 687 passing, 0 failing (plus 2 FEATURE_BUNDLE_1 fixtures, 57 → 57 incl. the new ones).

Areas covered

• Numeric boundaries (the audit's feat: import 2023-09 specification #1 finding: every string-length boundary was covered on both sides, every numeric boundary on neither): INT default/minValue/maxValue/allowedValues accepted at 2^63−1 and −2^63; FLOAT accepted at 1e308, rejected at 1e309/.inf/.nan; supplied INT value at 2^63−1 runs, at 2^63 rejected at job creation.
• Inclusive boundaries: value == minValue/maxValue accepted for INT and FLOAT; length == minLength/maxLength for STRING — an implementation using > for >= passed the old suite.
• onExit runs: verified there was previously no base job fixture containing an onExit action at all; marker-based fixture added.
• Cancelation defaults: TERMINATE + notifyPeriodInSeconds rejected; cancelation with no mode rejected; format-string mode rejected without FEATURE_BUNDLE_1.
• SimpleAction desugaring: scripts print their own argv, pinning the interpreter prefix and per-key file extension — previously wholly unasserted.
• Reference grammar: bare {{MyParam}} and four malformed dotted segments rejected — the inner-segment parser was previously untested.
• Cross-type misuse and closed objects: minValue on STRING, minLength on INT, unknown key in a parameter definition.
• Gating: let rejected in base step template and step script; bash: SimpleAction key rejected without FEATURE_BUNDLE_1.
• Post-resolution length: format-string job name resolving to exactly 128 chars accepted, 129 rejected — the normative "after resolution" check, previously only static-length-tested.
• Strengthened (edits): six 3.4.3 associative-combination job fixtures gained off-diagonal forbidden: lines. Before this, an implementation computing a full cross product where the spec requires a zip passed all six.

Deliberately excluded

Cases blocked on spec defects recorded in the audit (descending-range semantics where the spec's own example table contradicts both implementations and four existing fixtures; <posintstring> gating; maxLength: 0) — those need spec decisions first, not fixtures.

Companion PR

Spec-correct fixtures that FAIL against current implementations (the int64 template-validation acceptance family, the base type-name case gate, §1.2.1 merge widening) are in the expected-failures PR (branch conformance-base-expected-failures).