chore(cursor): add CORE dev environment (graphify install + attribution hygiene)

[real-limitless]

Summary

Sets up the Cloud Agent development environment for the ProjectEverflow CORE checkout, which previously had no .cursor/environment.json. Brings this repo in line with the sibling CORE repos (e.g. OpenFlow) that already run a per-boot attribution-hygiene start command, and provisions the graphify knowledge-graph CLI that AGENTS.md and the bundled skill rely on.

What changed

New .cursor/ files:

• environment.json — name, install, and start. Both commands search a list of known roots (cwd, workspace parent, and the absolute /agent/repos/projecteverflow path) and exec the first script found, so they work regardless of the agent's working directory.
• install.sh (idempotent) — pip install --user --upgrade graphifyy and adds pip's --user script dir to PATH so graphify query|path|explain|update work out of the box.
• strip-cursor-attribution.sh (start, per-boot) — removes Cursor *co-author* git hooks, installs a commit-msg.cursor.zz-strip-attribution scrub hook into every hook set, overrides a Cursor Agent git identity, and keeps a reaper so the co-author hook cannot linger between commits. Prints an OK/FAIL proof line.
• hooks/commit-msg-strip-cursor-attribution — the commit-msg hook that strips Co-authored-by: Cursor, Made/Generated with Cursor, and cursoragent@cursor.com lines.

Validation

• Clean environment build: draft build bld-20260910-27e2a3b9-c019-4471-a5ea-aa2812fa88ab pinned to this branch SUCCEEDED — install installed graphifyy-0.9.57 and logged graphify CLI ready. Two earlier builds surfaced a working-directory path issue in the multi-repo build harness; the absolute-root fallback fixes it.
• Install: idempotent (repeat run: "Requirement already satisfied").
• Start: removed 8 commit-msg.cursor.co-author files across the workspace (→ 0), installed the strip hook into every hook set, overrode the Cursor Agent identity to the repo owner, and started the reaper. Proof line: OK — no commit-msg.cursor.co-author or *co-author* files.
• App run: built a graphify knowledge graph of this repo (22 nodes / 23 edges / 4 communities) and exercised graphify query, graphify explain, and graphify path. Runtime output lives under the gitignored graphify-out/ and is not committed.
• Every commit on this branch carries zero Cursor attribution (no Co-authored-by trailer; authored by the repo owner, not cursoragent@cursor.com).

The committed .cursor/environment.json is repo-file-managed and takes precedence over dashboard config once merged. Environment changes affect newly started agents; this does not rebuild the current running agent.