feat: publish the fidelity tiers against both denominators they are read against

[skyoo2003]

Summary

Registering the 226 services the demand study found nobody building enlarged a denominator and nothing else, but the coverage page reported it as depth — hand-verified read 23.6% where it had read 36.2% without one operation becoming less faithful. The per-operation table now publishes both denominators, and every page that restates the share is gated against the binary.

Related Issue

Refs #166

Changes

Published figures

• docs/coverage.md splits the per-operation table into Serving target (the depth promise: every registered service except the 226) and All registered (the long tail added back, with the 6,794 operations that exist so an SDK call cannot leave for a billable account).
• Both hand-verified shares are published — 36.2% and 23.6% — with the denominator named where each is read. docs/fidelity-manifest.md gains the same note.

Derivation

• The serving-target set is derived from docs/demand.md (registry minus exactly the rows with support < 2) rather than pinned, so 205 does not gain a fourth home.
• The share is carried as integer tenths of a percent, so the gate and the updater compare the digits the page shows rather than two floats agreeing to a precision no reader can see. Rounded half up.

Gates (five → nine)

Test	Gates
TestPublishedOperationTiersMatchTheManifest	the operation tiers, in both denominators
TestPublishedFidelityShareMatchesTheManifest	the hand-verified share of each
TestPublishedLongTailProseMatchesTheManifest	the long-tail figures the prose states in words
TestFidelityManifestQuotesTheSameShare	that the manifest page states the same share
TestPublishedTargetTableMatchesTheBinary	(extended) that the table's 205 is the denominator the tier table divides by

Weekly sync

• figureEdit carries a render function instead of a separated bool — the page shows three renderings now (plain, thousands-separated, one decimal place) and the cell decides which.
• The updater owns six new spans across two pages, including docs/fidelity-manifest.md as a fourth target, and is idempotent on the committed pages.

Files Changed

File	Type
cmd/devcloud/coverage_test.go	Modified — two new gates, the denominator assertion, shareTenths, demandSupport
cmd/devcloud/figures_update_test.go	Modified — render functions, formatTenths, six new edits, three new round-trip cases
docs/coverage.md	Modified — two-denominator table, the paragraph explaining it, gate list
docs/fidelity-manifest.md	Modified — a tier share needs its denominator named
changes/unreleased/Changed-20260913-184045.yaml	Added

Test Plan

Every new gate was proved to bite before it was trusted — the figure was mangled in the tracked page, the gate was run, and the page restored:

Guarantee	RED evidence	GREEN
The published 205 is the tier table's actual denominator	target row → 206: promises depth on 206 … counted over 205	restored, PASS
The prose 6,794 matches the columns' difference	→ 6,795: states 6795 … columns differ by 6794	restored, PASS
fidelity-manifest.md agrees with coverage.md	→ 36.3%: states 36.3% … publishes 36.2%	restored, PASS
The updater owns the six new spans	round-trip cases 8–10 failed before the figureEdits existed	PASS
shareTenths rounds half up, not truncates	TestShareRendersTheFigureThePageShows — 1/8 → 12.5, 0/0 → 0.0	PASS

go test ./...                     119 packages ok
go vet ./cmd/devcloud/            clean
golangci-lint run ./cmd/devcloud/ 0 issues
gofmt -l cmd/devcloud/            clean
DEVCLOUD_UPDATE_DOCS=1 go test -run TestUpdatePublishedFigures
                                  PASS, working tree unchanged (idempotent)

Checklist

• Self-reviewed the code
• Added/updated tests
• Lint/format passes (golangci-lint run)
• Updated documentation (if applicable)
• Added a Changie changelog fragment for user-facing changes