Promo Message Improvements (streaming-time promos)

Implementation (shipped in this PR)

promo_click PostHog event (with messageId), exempted from the non-Pro 10% sampling in shouldBypassNonProTelemetrySampling — promos only show to non-Pro users, so sampling would have dropped 90% of clicks.
Pro promo clicks open the in-app DyadProTrialDialog (no browser context switch); the dialog now takes a utmCampaign prop so checkout/learn-more traffic is attributed per message (streaming-promo-<messageId>).
Promo is picked at stream start and persists after the stream ends; a new stream rotates to a new one. Hidden in test mode to keep e2e snapshots stable.
Rotation rebalanced: 4 Pro promos (trial, Agent mode, Pro tools, all models) at 3x weight vs 3 community tips (GitHub, Reddit, X) at 1x → ~80% Pro. Dropped Smart Context/Turbo Edits and doc tips.
Visual: bordered card using theme tokens (dark-mode safe), button-styled CTA, dismiss "×" that suppresses promos for 7 days via localStorage.
Skipped per decision: impression events, contextual/quantified copy.

Shown only while isStreaming to non-Pro users (!settings?.enableDyadPro && !userBudget), then disappears the moment the stream ends — exactly when the user's attention returns to the chat.
Small text-only banner: bg-blue-50 text-blue-700, no dark-mode variants (looks broken/harsh in dark theme, which most devs use).
12 messages rotate randomly by hash; only 2 of 12 are Pro promos (~17% of impressions). The rest are community/docs tips (Reddit, GitHub star, roadmap, report-a-bug).
Zero analytics: no PostHog impression/click events, no UTM params on the promo links (every other upgrade surface in the app has utm_campaign). We can't measure CTR or conversion per message.
No frequency capping, no dismiss, no targeting — the same random banner on every stream forever → banner blindness.
Messaging is feature-jargon-led ("Turbo Edits", "Smart Context") with no offer. Meanwhile the app has a 7-day free trial (trialCode=7PRO30, used by DyadProTrialDialog/SetupBanner) that none of these messages mention.

Ephemeral + mid-task: users watch code stream; clicking a link mid-stream context-switches them to a browser while their build is running. The moment of attention is right after the stream, and that's when we remove the banner.
Looks like an info notice, not an offer — no icon, no button, no visual weight.
Diluted inventory: 83% of the slot is spent on non-conversion tips.
No offer, no proof, no numbers: "Get Dyad Pro for faster edits with Turbo Edits" means nothing to someone who doesn't know what Turbo Edits is.
Unmeasurable: no way to know which message works.

Promo click → open existing DyadProTrialDialog (no context switch, stream keeps going).
Dialog already sells the trial and routes warm traffic to checkout with trial code.

Keep the promo visible after streaming completes (until next user message, or dismissible), or animate it into a slightly stronger card on stream end: "That took 84s — Pro's Turbo mode is ~2x faster."

Lead with the trial: "Try Dyad Pro free for 7 days" beats "Get Dyad Pro".
Use real numbers from the session where possible (tokens sent → Smart Context savings; elapsed stream time → speed; error/retry detected → Agent mode auto-debugging).
Benefit language, not feature names: "Stop juggling API keys — one plan with GPT-5.5 + Claude Opus", "Fix errors automatically with Agent mode".

Split tips from promos. Streaming slot: mostly Pro promos for users past an engagement threshold (e.g. >N messages / >1 app); tips for brand-new users.
Move community tips (Reddit, GitHub star) to low-intent surfaces: empty states, post-deploy success.

Sparkles/gradient accent consistent with DyadProTrialDialog, real button-styled CTA, dark-mode support, subtle fade-in.
Optional dismiss ("×") that suppresses promos for ~7 days.

Cap impressions per day; escalate offer strength with usage; stop showing a message a user has clicked.

Education-style messages (user may not know what Pro is) → https://www.dyad.sh/pro?utm_... — consideration page, low bounce.
Direct-offer messages ("Start your free 7-day trial") → https://academy.dyad.sh/redirect-to-checkout?trialCode=7PRO30&utm_... — same pattern the app already uses. Prefer this over hardcoding /sign-in?redirect_url=...: the redirect endpoint owns the auth flow (survives auth changes) and carries the trial code.
Best of both: click → in-app DyadProTrialDialog, which offers "Start Free Trial" (checkout) and "Learn more" (/pro). Warm the user before the sign-in wall.