docs(testing): describe the test strategy without publishing it

[hhimanshu]

Closes #64.

The page documented the conformance harness in enough detail to be a build guide — the capture mechanism and the tool behind it, exact fixture paths, the internal test-macro name, a pipeline diagram, and the file naming for known differences.

None of that helps a reader decide whether to trust the engine, and all of it is reusable by anyone wanting to build the same thing. The corpus is the hard part and the durable advantage; the page should carry the confidence without handing over the recipe.

Kept — these are the actual reasons to trust it, and they're arguments, not instructions:

• Reference values come from Google Sheets itself, not from a specification and not from our own output
• Why that matters: an engine checked against itself can only ever agree with itself
• Enforced vs tracked categories, and how to read them
• Known differences stay in the total rather than being removed — a conformance number that excludes its own failures isn't evidence
• Reference integrity: values are never hand-edited, and reference data never travels with an engine change

Removed — the capture tooling and pipeline wiring, exact fixture paths, internal test-macro names, the diagram, and the internal naming for the known-differences set.

Net effect: shorter, and it now reads as why this is trustworthy rather than how to rebuild it.

The same edit has been applied to the corresponding section of the marketing site (truecalc/website#2), so the two stay consistent.

🤖 Generated with Claude Code

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