## What does this PR do?
Fixes a bug where custom tarball URLs get corrupted during installation,
causing 404 errors when installing packages from private registries.
## How did you test this change?
- Added test case in `test/cli/install/bun-add.test.ts` that reproduces
the issue with nested tarball dependencies
- Verified the test fails without the fix and passes with it
- Tested with debug build to confirm the fix resolves the URL corruption
## The Problem
When installing packages from custom tarball URLs, the URLs were getting
mangled with cache folder patterns. The issue had two root causes:
1. **Temporary directory naming**: The extract_tarball.zig code was
including the full URL (including protocol) in temp directory names,
causing string truncation issues with StringOrTinyString's 31-byte limit
2. **Empty package names**: Tarball dependencies with empty package
names weren't being properly handled during deduplication, causing
incorrect package lookups
## The Fix
1. **In extract_tarball.zig**: Now properly extracts just the filename
from URLs using `std.fs.path.basename()` instead of including the full
URL in temp directory names
2. **In PackageManagerEnqueue.zig**: Added handling for empty package
names in tarball dependencies by falling back to the dependency name
🤖 Generated with [Claude Code](https://claude.ai/code)
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Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
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