[Docs] Integrate 26.07 documentation PRs and stage the version train

Parent tracker: NVIDIA-NeMo/Curator#2118

Goal

Integrate the 26.07 documentation PR set without losing content at cross-PR merge boundaries, then stage the version train for publication.

Why this is required

An adversarial combined-tree merge found four real content-conflict groups even though the individual PRs pass validation:

• NVIDIA-NeMo/Curator#2135 and #2136 both add cards to the audio overview and tutorial index.
• NVIDIA-NeMo/Curator#2134 and NVIDIA-NeMo/Curator#2142 both extend the ProcessingStage API reference.
• #2130 and #2149 both extend the semantic deduplication page at the same insertion point.
• NVIDIA-NeMo/Curator#2143 and NVIDIA-NeMo/Curator#2147 both update the release-notes page. NVIDIA-NeMo/Curator#2143 is the canonical 26.07 rollup and must preserve the typed InferenceServer/Dynamo material.

Timing

Release blocker. Perform the reconciliation after the detailed feature PRs merge, but before NVIDIA-NeMo/Curator#2143 merges and before any docs/v1.3.0 publication tag is pushed.

Acceptance criteria

• Merge or rebase the audio pair and preserve both tutorial cards on both landing pages.
• Merge or rebase the resumability/worker-sizing pair and preserve both task-lineage and backend-configuration sections.
• Merge or rebase the deduplication pair and preserve both input-discovery and K-means fitting guidance.
• Merge NVIDIA-NeMo/Curator#2147 before NVIDIA-NeMo/Curator#2143, then rebase NVIDIA-NeMo/Curator#2143 and preserve the complete 26.07 release narrative.
• Run fern check, git diff --check, and the generated-reference broken-link job against the combined tree.
• Stage v26.07, update fern/docs.yml, redirects, and the latest.yml symlink according to the version ship checklist.
• Do not push the production docs/v* tag until release authorization is explicit.