feat: Scope oauth tokens by org, replace flat project list with org-keyed map

[charlesvien]

Issue: #1101
PostHog/posthog PR: PostHog/posthog#50725

1. Replace flat availableProjectIds/availableOrgIds arrays with org-keyed orgProjectsMap in auth store
2. Add listOrgProjects API method and buildOrgProjectsMap helper to fetch projects per organization
3. Remove scoped_teams from OAuth token response schema and stored tokens
4. Simplify useProjects hook to derive project list from org map instead of fetching user data
5. Move currentUser query out of useProjects into ProjectSwitcher where it's actually used
6. Update mobile auth store to drop scoped_teams dependency

[charlesvien]

• fix: Reduce agent eagerness to re-enter plan mode mid-task #1208
• feat: Scope oauth tokens by org, replace flat project list with org-keyed map #1210 👈 (View in Graphite)
• feat: Add multi-agent command center grid view #1212
• feat: Add effort level control for Claude sessions #1211
• feat: Optimistically render conversation items before subscription confirms #1209
• feat: Add idle timeout to kill inactive sessions after 15 minutes #1207
• fix: Fix corrupted view redirect, workspace cache flash and diff collapse #1206
• main

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