docs(roadmap): record Track D status after the vocabulary, repository and API-form work

[devin-ai-integration]

What and why

docs/project/roadmap.md still described Track D as it stood before #507, #509, #519 and #523 landed: D1, D2 and D9 carried no status marker, the "what remains open" and cross-cutting order still listed "D2 and D1" as the next Flexo step and gated B4's Flexo provider and D10 on D9.2, and the track-local summary quoted the RDF ratchet at 353/353 with D8 "only conformant behind D1 and D2".

This brings the roadmap in line with develop:

• D1, D2 and D9 marked done; D8 and D10 named as what remains in Track D.
• Cross-cutting step 3 (D2 and D1) marked landed, with the live-stack harness re-recorded at 505/582 properties.
• D9.2 gating language removed from B4 and D10.
• Current develop figures stated beside the v0.8.0 gate table: validation census 163/217 (157 faithful, 6 approximate, 0 not implemented, 1 deliberate, 53 unknown), RDF corpus round trip 356/356, API element-form round trip 354/356.

No other file changes; spec-compliance.md, README.md, the guide and reference pages were checked and already match the tree.

How it was verified

Full gate on develop at 9d67a0235 before editing: go build, go vet, gofmt -l (empty), go test ./..., the four corpus/identity gates with their require variables set, make docs-check, make man-check, make docs-counts (already current), python3 scripts/changelog.py check — all pass, and the figures above are the ones those gates printed.

On this branch: make docs-check, make docs-counts (already current), python3 scripts/changelog.py check.

Checklist

• make test and make lint pass locally
• Tests added or updated for the change (docs only)
• Documentation extended where it already covers the surface (see CONTRIBUTING.md)
• Changelog entry added (roadmap-only edits carry no fragment, as before)
• baselines regenerated and make docs-counts run if a gate count moved (no count moved; docs-counts is current)
• No internal work-item labels (waves, slices, F4, K5) in the body, docs, or changelog

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring

[devin-ai-integration]

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