Distilled from #789 (safe features only). Adds backend dead-code classification
(status + in_calls in the layout JSON), a GET /api/repo-info endpoint for GitHub
deep-links, and the frontend dead-code filters, node code preview, and deep-links.
The render-cap revert was dropped (kept 2000 for DEFAULT_MAX_NODES/HARD_MAX_NODES
and GRAPH_RENDER_NODE_LIMIT); the sidebar regex-search refactor was omitted.
Security fixes over the original: repo-info strips credentials from any returned
remote_url; the legitimate https blob-URL construction is allow-listed so the
static gate passes; libgit2 is not re-initialized/shutdown per request (reuses the
process-wide init from cbm_alloc_init); deep-link path segments are URL-encoded.
Co-authored-by: Andy Zehady <azehady@ciroos.ai>
Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>
