Arc URL resolution now honors launchSettings.json and defaults to localhost:5000

[Copilot]

Summary

Arc commands previously fell back directly to a hardcoded default URL when --url/ARC_URL were unset, which missed common local Arc setups. This change adds launchSettings.json discovery (Properties/properties) and aligns the default Arc URL with Arc app defaults.

Added

• Added launch settings URL discovery in Arc settings resolution by reading profiles.*.applicationUrl from Properties/launchSettings.json or properties/launchSettings.json (#issue)

Changed

• Updated Arc URL resolution precedence to: --url → ARC_URL → launchSettings.json applicationUrl → default (http://localhost:5000) (#issue)
• Updated Arc command examples and Arc docs to reflect http://localhost:5000 as the default URL and the new resolution order (#issue)

// Effective Arc URL resolution
if (--url is set) return url;
if (ARC_URL is set) return env;
if (launchSettings.applicationUrl exists) return applicationUrl;
return "http://localhost:5000";

Fixed

• Fixed Arc CLI behavior for local projects where runtime URL is configured in launch settings but not passed as a flag/env var (#issue)
• Fixed mismatch between documented/default Arc URL and expected Arc local default (http://localhost:5000) (#issue)

Removed

• Removed implicit assumption that Arc URL fallback is only an env var + hardcoded default path (#issue)

Security

• No security behavior change; launch settings parsing is local-file, read-only, and guarded for invalid/unreadable JSON (#issue)

Deprecated

• No deprecations in this PR (#issue)