enhance(spec-phase): edge-probe precision probe should name tie-breaking / rounding-mode (#1108)

* feat(spec-phase): name tie-breaking/rounding mode in the edge-probe precision probe (#1102)

The precision edge probe fired on numeric-range requirements but its text never
named the most common rounding failure mode — tie-breaking / rounding mode
(half-up vs half-to-even, ceil/floor/truncate). In an A/B experiment the weak
tier (haiku) false-passed 50% of tie-class defects against the surfaced-
unresolved spec; naming the rule in the probe text drove honest abstention
83%→100% (false-pass 17%→0%, haiku 50%→0%) with no category regression
(precision still fires only on numeric-range).

Sharpen the single TAXONOMY probe string and update every rendering together so
the doc↔fixture↔machine contract (edge-probe-docs-fixtures.test.cjs) stays green:
src/edge-probe.cts, the edge-probe.md taxonomy table + 2 worked examples, the
01-round-half-even and 04-money-rounding fixtures, and the resolve-edge-coverage
how-to. Prose-only — no consumer keys on the probe text; SHAPE_CUES firing
unchanged; fully backward compatible.

* chore(changeset): Changed fragment for edge-probe precision probe text (#1108)

src/edge-probe.cts

@@ -88,7 +88,7 @@ export const TAXONOMY: TaxonomyEntry[] = [
   { id: 'empty', name: 'Empty / degenerate', shapes: ['collection', 'text'], probe: 'What is the result for empty, single-element, or null input?' },
   { id: 'encoding', name: 'Encoding / representation', shapes: ['text'], probe: 'Whose definition of length/equality applies — bytes, code points, grapheme clusters, or normalized form?' },
   { id: 'ordering', name: 'Ordering / stability', shapes: ['collection'], probe: 'When elements compare equal, is output order specified and stable?' },
-  { id: 'precision', name: 'Precision / overflow', shapes: ['numeric-range'], probe: 'Where can precision loss or overflow occur, and what is the contract?' },
+  { id: 'precision', name: 'Precision / overflow', shapes: ['numeric-range'], probe: 'Where can precision loss, overflow, or rounding/tie-breaking occur — and what is the exact contract (e.g. half-up vs half-to-even, ceil/floor/truncate)?' },
   { id: 'idempotency', name: 'Idempotency / repetition', shapes: ['stateful'], probe: 'What happens if this runs twice on the same input?' },
   { id: 'concurrency', name: 'Concurrency / effect ordering', shapes: ['stateful', 'io'], probe: 'If interrupted or run in parallel, what is guaranteed?' },
 ];