Two fixes for Camanji rate limit UX:
1. api/streaming.py — pass fallback_model from profile config to AIAgent
The agent already supports fallback_model (a dict with provider/model/base_url)
for automatic rate-limit recovery, but streaming.py never read it from config
or passed it to AIAgent. Now reads get_config().get('fallback_model') at
call time (not module-level snapshot) and passes it through.
Also reads platform_toolsets.cli from the active profile's config at call
time so profiles with custom toolset lists use the right tools.
Camanji has fallback_model: {provider: openrouter, model: anthropic/claude-sonnet-4.6}
so hitting the direct-Anthropic rate limit will now automatically retry via
OpenRouter before giving up.
2. api/streaming.py + static/messages.js — show error inline, not 'Connection lost'
Previously: agent threw -> put('error', msg) -> SSE connection closed ->
browser's network-level 'error' event fired -> generic 'Connection lost'.
The actual error message was invisible to the user.
Fix: renamed server-side error event to 'apperror' (distinct from the SSE
spec's network error event). Added source.addEventListener('apperror', ...)
in messages.js that renders the error as a styled assistant message:
⏱️ Rate limit reached: <full message>
*Rate limit reached. Fallback model exhausted. Try again in a moment.*
Also added source.addEventListener('warning', ...) for non-fatal notices
(future use: fallback-activated status bar update).
Tests: 426 passed, 0 failed.