Bash sandbox default denies git push/fetch, npm install/build, and loopback-only Postgres

**Summary**

In a standard full-stack repo (Node/Next.js + Prisma/Postgres, hosted on GitHub), nearly every git/npm/gh command that touches the network fails under the default Bash sandbox with "Operation not permitted": `git push`, `git fetch`, `npm ci`, `npm run build`, `npx prisma migrate deploy`/`generate`, `gh pr create`/`merge`. So does purely loopback Postgres access (`psql -h localhost`, `createdb`, `dropdb`), which isn't external network traffic at all.

**Impact**

In a same-day survey of 14 concurrent Claude Code sessions working on one private repo, 6+ sessions independently flagged this as their single largest source of friction. One session logged 15+ separate escalations to `dangerouslyDisableSandbox` for entirely routine git operations in a single sitting. In a repo where nearly all useful work is git/npm/gh, the sandbox default barely narrows anything down — it's a retry round-trip on almost every command rather than a meaningful safety boundary.

**Reproduction**

1. Open a Claude Code session in any git repo with a configured remote and a local Postgres database.
2. Ask it to run any of: `git push`, `git fetch`, `npm ci`, `npx prisma migrate deploy`, `psql -h localhost -p 5432 -c '\dt'`.
3. Observe "Operation not permitted" under the default sandbox; the same command succeeds immediately with `dangerouslyDisableSandbox: true`.

**Suggested fix**

Default-allow loopback destinations (127.0.0.1/::1) and the git remote host(s) already configured for the current working repo. These are the expected baseline for nearly any software project's day-to-day workflow, not an edge case that should require an escalation every time.

Start by locating the default Bash sandbox's network-permission handling and its tests; the issue names git push/fetch, npm ci, Prisma commands, gh operations, and loopback psql as reproduction points. Compare default behavior with dangerouslyDisableSandbox and determine how configured git remote hosts and 127.0.0.1/::1 are represented; done means these routine commands work without escalation while unrelated network access remains restricted.

Written by the indexing model from the issue text.