fix(desktop): scope restored navigation by profile (#67709)

[kshitijk4poor]

What changed

Salvage of #67823 (cc @Tranquil-Flow), rebased onto current upstream/main to resolve the modify/delete conflicts in use-desktop-integrations.ts and wiring.tsx and the content conflicts in session.ts and session.test.ts.

The original PR's intent is preserved in full:

• Scope remembered desktop route and session keys by the encoded active profile
• Discard ambiguous legacy global navigation keys instead of assigning them to an arbitrary profile
• Delay cold-start restoration until the primary profile and session list have reached renderer.ready
• Preserve explicit deep-link and hidden-window destinations
• Restore and persist session routes only when a direct ID or lineage root is explicitly owned by the active profile
• Clear both profile-scoped route and session state after resume exhaustion

Conflict resolution

upstream/main landed two changes in the same files since the original PR was authored:

1. fix(desktop): scope the remembered route per profile #74277 (merged) added per-profile route key scoping with LAST_ROUTE_KEY declared separately further down in session.ts. This salvage consolidates LAST_ROUTE_KEY next to LAST_SESSION_KEY at the top, removes the duplicate declaration, and keeps the module-level legacyDiscardNeeded flag with _resetLegacyDiscardForTests() export for test isolation.

2. Commit 143942d restructured wiring.tsx to call useDesktopIntegrations with $activeGatewayProfile.get() and $desktopBoot.get() (non-reactive .get() calls). This salvage converts both to reactive useStore() subscriptions (activeGatewayProfile and boot) so the profileReady gate and activeProfile prop update correctly when the boot phase or active profile changes.

The use-desktop-integrations.ts hook itself was applied cleanly from the original PR — no modifications to its logic were needed.

Why

The partial fix in #74277 scopes route keys but does NOT gate restoration on profile readiness or validate session ownership, so the race window is still open on current main. Users on v2026.8.3 with multiple profiles still see:

• Chats appearing under the correct profile but opening another profile's transcript when duplicate session IDs exist
• New empty Default-profile copies being created on every cold start
• Session IDs existing in multiple profile databases with different histories

This salvage closes all three layers: profile-scoped keys, renderer.ready gate, and explicit session-ownership validation.

Verification

• TypeScript renderer + Electron typecheck: passed (tsc --noEmit)
• ESLint on all five changed files: passed (0 errors, 0 warnings)
• Focused regression suite: 71/71 passed (session.test.ts + use-desktop-integrations.test.tsx)
• Production desktop build including assert-dist-built: passed
• git diff --check: passed
• Branch shape: exactly 1 commit ahead of current upstream/main

Related

• Closes Desktop cold-start restore can resume a session into the wrong profile and create duplicate session IDs #67709
• Salvages fix(desktop): scope restored navigation by profile (#67709) #67823 (original PR by @Tranquil-Flow — authorship preserved)
• Supersedes the partial route scoping from fix(desktop): scope the remembered route per profile #74277 (merged)