docs: record 1.0.0 release readiness baseline

[rogerdigital]

Summary

Execute T0 of the 1.0.0 release readiness plan (docs/superpowers/plans/2026-09-12-1.0.0-release-readiness.md):

• Create docs/releases/1.0.0/readiness.md, the evidence record with the ten-gate status table initialized from a fresh baseline run.
• Mark T0 complete in the plan checklist.

Baseline evidence (2026-09-15)

• Source commit: 2915687 on a clean checkout, branch fix/1.0-export-integrity.
• Runtime: Node v24.16.0, npm 11.13.0, macOS 27.0 (arm64).
• npm run check:version — pass ("Version metadata is consistent: 0.7.4")
• npm run lint:obsidian-warnings — pass
• npm run build — pass
• npm test — 20 files, 360 tests passed
• Remote (read-only): 0 open issues, 0 open PRs; release 0.7.4 with three assets; latest verify runs green including HEAD 2915687.
• No vault plugin symlink present on this machine, so builds cannot update a live plugin.

Documentation-only change; no code or behavior changes.