Retire strict_provenance docs; drop provenance terminology

[dimitri-yatsenko]

Documentation counterpart to datajoint/datajoint-python#1489 (retire the strict_provenance runtime guardrail), and alignment with the decision to keep provenance terminology out of DataJoint's own documentation.

DataJoint implements the relational workflow model — data integrity, consistency, lineage, and reproducibility. "Provenance" is associated with a different class of systems; DataJoint's provenance compatibility features live in the platform and are documented separately (datajoint-provenance). So the public docs use the model's native vocabulary: lineage, reproducibility, traceability.

Stacked on #198 (base branch docs/197-make-contract). This PR links to the make() reproducibility contract section added there. Merge #198 first; GitHub will retarget this PR to main automatically.

Changes

Retire strict_provenance:

• Rename reference/specs/provenance.md → reference/specs/trace.md and rewrite it as the spec for the upstream read surface (Diagram.trace + self.upstream) — the strict_provenance section (§3), config docs, examples, and references are removed; the "read/write boundary" is reframed in lineage/reproducibility terms.
• about/whats-new-23.md: reframe the "provenance trinity" as the trace + self.upstream pair, drop the strict_provenance subsection and adoption step, retarget links.
• mkdocs.yaml: nav "Provenance Trace & Strict Provenance" → "Upstream Trace".

Drop "provenance" terminology across the conceptual and tutorial pages (index, about/index, relational-workflow-model, normalization, comparison-to-workflow-languages, schema-as-workflow-specification, data-pipelines, faq, and three tutorial notebooks) — replaced with "lineage" / "reproducibility" / "traceability" per context.

Verification

• grep confirms no "provenance" terminology remains in tracked source (src/), and no links point to the old specs/provenance.md path.
• The renamed page and all retargeted cross-links resolve; anchor slugs verified. (llms-full.txt is a generated, untracked build artifact — regenerated on build.)

Published URL

reference/specs/provenance/ becomes reference/specs/trace/. This PR adds mkdocs-redirects (and the mkdocs-redirects build dependency) so the old URL redirects to the new page instead of 404-ing.

[MilagrosMarin]

Thanks @dimitri-yatsenko — nicely-scoped counterpart to datajoint-python#1489. Verified end-to-end.

The retirement side is clean: provenance.md (441 lines, the strict_provenance spec) becomes trace.md (301 lines, focused on the Diagram.trace + self.upstream pair). grep for strict_provenance, assert_read_allowed, assert_write_allowed, contextvars.ContextVar, and "Enforcement model" in the new file all return empty — the flag content is fully purged, not just relabeled. The what's-new-23.md reframe from "provenance trinity" to "trace + self.upstream pair" drops the "Enable strict_provenance=True in staging" migration step cleanly. mkdocs.yaml nav renames "Provenance Trace & Strict Provenance" → "Upstream Trace" and adds the redirects plugin (with pip_requirements.txt picking up mkdocs-redirects) so the old /specs/provenance/ URL doesn't 404. Cross-link to autopopulate.md#43-the-make-reproducibility-contract resolves against the anchor introduced in the stacked #198.

The terminology sweep across the conceptual pages reads well. "Provenance" mostly becomes "lineage" in contexts about tracing derivation ("Queries trace provenance" → "Queries trace lineage", "Rows carrying provenance to their inputs" → "traceable to their inputs"), and "provenance and lineage" (previously redundant) collapses to "lineage and reproducibility". Section labels in the Codd/Chen/RWM comparison table follow: "Provenance" → "Data lineage". Consistent choice per context.

One residual worth calling out: grep -rni "provenance" src/ returns one hit — src/images/dj-platform.svg:155 still lists "Reproducibility • Provenance • Integrity • Collaboration" in the platform-architecture text label. This is defensible under the PR's own framing (the platform's provenance-compatibility features live separately in datajoint-provenance), and the SVG is describing platform-side capabilities rather than framework docs. But the PR body's claim "no 'provenance' terminology remains in tracked source (src/)" is a slight overclaim — the SVG is tracked source. Either update the SVG to match the doc-side terminology reset, or tighten the PR-body claim to note the platform-diagram exception. Small.

Sequencing note (already flagged in the PR body): stacked on #198. Merge #198 first; GitHub retargets this one to main automatically. Verified this PR's diff isolates cleanly against upstream/docs/197-make-contract — 16 files, 341 insertions, 496 deletions.

Approving.