test(living-world): qualify negative environmental observations

[Tristan-Stoltz-ERC]

Summary

Fresh r2 replacement for the first test-only reference semantics for #1269 on top of frozen #1267.

Exact parent/base (#1267):

2c5de7b1d5f0f38317924ba69cd15a545694c3c6

Current exact subject:

ce592e521f84bae19ba77aa17fa76646cee9cc21

Current tree:

196967b59fadbec0944613f676e58677a885411f

Exactly one semantic commit over the same parent and exactly one added integration-test file:

crates/domains/symtropy-lifesim-core/tests/negative_observation_reference.rs

Why r2 exists

The original exact subject 9df3a60507a035e681714b86cbb5c134c5bdc0fb reached its hardened qualifier (#1272, run 35444413459) and failed at Rust 1.96 rustfmt --check. Checkout, exact scope, exact Rust/cargo family assertions, immutable postflight, evidence recording, and artifact upload all succeeded; tests/Clippy/check did not execute.

The runner emitted exactly one formatting hunk in unrelated_partition_mutation_does_not_stale_local_absence.

r2 was reconstructed as a fresh direct child of the original parent, not as a fix commit on the failed subject. Audit-only unreferenced commit 0d171d762edd47588e749624eecccbd7584b831f compares failed r1 to the r2 tree and proves the entire delta is exactly that runner-emitted formatting hunk and one file only.

Failed r1 remains historical negative evidence and no result transfers to r2.

Reference theorem

Environmental absence is a provenance-bearing authority claim, not an alias for missing data:

authority + spatial subject + membership generation + observation profile
        ↓
NoSubject(NegativeSubjectObservation)

The fixture proves:

• stable absence can be revalidated exactly;
• subject appearance invalidates prior absence;
• unrelated patch mutation does not stale a local absence proof;
• unavailable/unloaded representation yields Unknown, not NoSubject;
• a previously valid absence becomes invalid when the representation can no longer prove absence;
• an explicitly absence-capable coarse representation may prove absence;
• membership-generation changes stale old absence even if the patch is still empty;
• spatial rebinding invalidates prior absence;
• absence in one spatial subject cannot prove absence in another;
• below-threshold presence is distinct from no subject;
• observation profile identity is part of the negative evidence.

Evidence boundary

r2 is qualification-pending until a fresh exact-subject qualifier executes the unchanged semantic gate sequence:

1. Rust 1.96 exact-file rustfmt;
2. focused locked integration test;
3. strict focused Clippy;
4. focused locked check;
5. immutable postflight and retained evidence.

No PASS transfers from any predecessor.

Nonclaims

No universal cross-domain absence type, production vegetation index, durable persistence codec, production Terrain/ecology mutation, calibrated ecology, or multi-owner transaction is established.

Relates to #1269, #1267, #1268, #1253, #1260, #1264, #1275.