Fix CE URL scheme routing

[baron]

Summary

Fixes #77.

This fixes the RepoPrompt CE URL-scheme productization mismatch by making repoprompt-ce:// the canonical app deep-link scheme while preserving parser-level compatibility for legacy repoprompt:// URLs that are delivered to CE.

What changed

• Centralized accepted app URL schemes in AppDeepLinkURLScheme.
• Generated agent-session deep links now use repoprompt-ce://.
• App URL routing and legacy opener handling now accept the same scheme policy.
• Advanced Settings now shows the official CE URL opener scheme, examples, supported opener parameters, and the classic RepoPrompt coexistence caveat.
• Added tests for canonical CE routing, legacy parser compatibility, opener route classification, unsupported schemes, and the packaged CE URL scheme registration policy.

Why

RepoPrompt CE registers repoprompt-ce in its app bundle, but routing code was still expecting and generating repoprompt. That meant LaunchServices could deliver a valid CE URL to the app and the app would ignore it before reaching the opener path.

Validation

• .agents/skills/rpce-contribution-check/scripts/preflight.sh commit
• python3 Scripts/test_release_tooling.py -k test_info_plist_registers_canonical_ce_url_scheme_only
• make dev-lint
• make dev-test FILTER=AppPlatformUtilityRecoveryTests
• make dev-swift-build PRODUCT=RepoPrompt
• make dev-test
• make dev-test FILTER=AgentModeChatSwitchActivationTests after one transient full-suite failure in that unrelated suite
• .agents/skills/rpce-contribution-check/scripts/preflight.sh push passed on retry