Preserve held disposition in changed-witness standing

[gunbai-bot]

Work item node://adhoc-40803be0-645 (parent neat-swift-219).

The changed-witness projection collapsed KnownRedHeld into PlannedAndPassed, producing the contradictory line observed on #9727 (standing=planned-and-passed outcome=known-red-held). This changes the .dag authority first: ChangedWitnessExecutionStanding now has a distinct PlannedAndKnownRedHeld constructor, realized on the host wire as planned-and-known-red-held. Ordinary passing identities remain planned-and-passed.

This standing is not display-only: it feeds changed_witness_standing_blocks and therefore the required-floor decision. The new held constructor is explicitly non-blocking, preserving the sanctioned expected-red behavior while making the projected label honest. Exhaustive .dag matches carry the new arm, so omitted classifications refuse compilation.

RED/control evidence:

• planned_with_known_red_held_verdict_stands_green now requires the distinct held constructor; it would fail under the prior collapse.
• planned_with_passed_verdict_stands_green keeps the ordinary pass label.
• passed_and_known_red_held_are_green proves both decision polarities explicitly.
• Seed projection test asserts the exact planned-and-known-red-held wire label and outcome=known-red-held.

Verification:

• cargo test -p v1-compiler changed_witness_projection_tests --lib — 11 passed. BuildBuddy invocation: https://app.buildbuddy.io/invocation/d5ad2046-a884-4c01-a100-665ab5e3de88
• Direct modeled claims above — PASS. BuildBuddy invocation: https://app.buildbuddy.io/invocation/57e7cd9d-a92a-43ba-a9f0-fff17031aef7

Composition: #9725 also adds a constructor and match arms to floor_changed_witness.dag. The changes are semantically independent and trivially composable; this PR lands FIRST; #9725 then integrates the resulting main, preserving both exhaustive arms (PlannedAndKnownRedHeld from here, DeclinedRoutedToWetLane from #9725).

Hand-Rust receipt: v1_compiler.cli_run.required_floor_runner.changed_witness_projection_rows and emit_changed_witness_projection are ExistingSeedItemModified under gunbc.seed_growth_admission.SeedGrowthChangeDisposition; this change only re-arms those existing functions for the new modeled standing constructor. It adds zero module-scope Rust items and no new seed capability, so no SeedGrowthJustification row is due.

[gunbai-bot]

Addressed both findings from review 57572 in commit 14cb7cf.

• Replaced all five shape-recursive Boolean helpers with one exhaustive standing_kind projection, and converted every test to compare that canonical observation. This shrinks the test vocabulary from five coproduct traversals to one.
• Added the explicit hand-Rust receipt to the PR body: the Rust edits only modify the existing changed_witness_projection_rows and emit_changed_witness_projection items (ExistingSeedItemModified under gunbc.seed_growth_admission.SeedGrowthChangeDisposition), add zero module-scope Rust items, and introduce no new seed capability. Therefore no SeedGrowthJustification row is due.

— sent from swift-carp-293