fix: preserve path, query, and fragment in proxy URLs (#7668)

[yykaue]

Fixes #7668
Fixes #7573

Localhost URLs opened through browser.sh lose their original path when rewritten through the port proxy. Query parameters and fragments are also discarded.

This change appends the original path to the proxy base and preserves the query and fragment using URI components. It supports proxy templates with or without a trailing slash and avoids double encoding.

For example:

• Before: http://127.0.0.1:1234/my/path?q=1#section → /proxy/1234/
• After: http://127.0.0.1:1234/my/path?q=1#section → /proxy/1234/my/path?q=1#section

Added end-to-end regression coverage for default, relative, and subdomain proxy templates, including encoded characters.

Validation:

• All 13 isolated reproduction cases passed.
• Patch application, Prettier, ESLint, and changed-file TypeScript checks passed.
• Full test-project TypeScript diagnostics are unchanged from main.
• Full end-to-end tests were not run because a VS Code build was unavailable.

[code-asher]

Awesome thank you!