Migrate build publish and materialize scripts onto shared Python tooling helpers

[doublemover]

Parent inventory: #8108
Blocked by: #8119, #8120, #8123, #8124

Objective

Migrate build, publish, and materialize scripts onto shared Python tooling helpers without introducing a publisher framework.

Shared Module Specification

• Migrate repeated path, JSON IO, text/JSON write, subprocess, timed-step, Markdown, summary, and output-writing helpers in scripts/build_*, scripts/publish_*, and scripts/materialize_*.
• Keep report-specific schema construction local.
• Preserve generated artifact paths, report schemas, and public Markdown content unless intentionally fixing a validated bug.
• Prefer readability over maximum abstraction.

Migration Checklist

• Migrate file/path/JSON helpers first.
• Migrate command-result helpers second.
• Migrate Markdown/report primitives third.
• Migrate parser option groups only where concrete and identical.
• Run changed scripts in batches and compare durable output shape where practical.

Inventory

• Replacement scope is every matching helper occurrence from the Python inventories in the path/JSON, subprocess, report, and CLI-option issues that lives in scripts/build_*, scripts/publish_*, or scripts/materialize_*.
• High-risk helper groups: write_text, write_json, render_markdown, render_markdown_report, build_summary, build_summary_payload, write_outputs, run_step, and ensure_success.

Performance And Reliability Requirements

• Keep helper code small, dependency-light, and fast enough for normal development feedback.
• Add focused tests for edge cases before broad migration.
• Preserve existing output schemas and public behavior unless an intentional bug fix is validated.
• Keep production helpers separated from test-only helpers.
• Do not use tmp/ as durable source-of-truth; generated temporary files are allowed only as transient command inputs.

Fast Tests

• Run python -m py_compile for every changed build/publish/materialize script.
• Run focused scripts that write JSON and Markdown artifacts.
• Compare generated outputs for stable key ordering, newline policy, and path rendering.
• Run affected npm/public workflow commands after migration batches.

End-To-End Completion Criteria

• Build/publish/materialize scripts use shared primitives for generic work.
• Report-specific logic remains local and readable.
• Generated artifacts remain deterministic and schema-compatible.