Release EdgeCrab v0.9.0

[raphaelmansuy]

Summary

Release EdgeCrab 0.9.0 with the new Shadow Judge completion oracle and the accompanying harness/tool hardening.

What changed

• add the opt-in Shadow Judge completion oracle, session toggle, and status-bar intervention UI
• add structured report_task_status/completion-assessment hardening and semantic invalid-argument retry suppression
• add machine-readable tool metadata improvements for file write/patch/search/terminal results
• update release-facing README and Astro docs, and promote the changelog entry into the 0.9.0 release notes
• sync the canonical workspace/package versions to 0.9.0

Validation

• ./scripts/release-version.sh check
• cargo test -p edgecrab-core --lib
• cargo test -p edgecrab-tools --lib
• cargo test --workspace succeeded in the original checked-out repo state before branch packaging
• corepack pnpm build in site/ with Node 22.12.0

Notes

• Local cargo clippy --workspace --all-targets -- -D warnings in the fresh clean worktree is blocked by missing cmake for the boring-sys2 dependency on this machine; GitHub CI should be the authoritative lint gate for this PR.