feat(ui): wire Welcome screen CTAs to Scanner navigation + external browser

[ilmoniemi]

User Story

As a new Pyrycode Mobile user on the Welcome screen who hasn't yet set up the pyrycode CLI, I want the Set up pyrycode first CTA to open the setup landing page in my browser so I can install pyrycode without leaving the app guessing where to go.

Context

The Welcome screen's two CTAs were scaffolded in #7 with hoisted onPaired / onSetup callbacks. #12 (merged in PR #41) already re-wired onPaired at the MainActivity PyryNavHost layer to navigate to Routes.Scanner — that half of the original #14 is done. What remains is the onSetup callback, which is still a TODO(#14) placeholder at MainActivity.kt's composable(Routes.Welcome) { ... } block.

This ticket wires that one callback to an external-browser launch via Intent.ACTION_VIEW + Context.startActivity, pointing at https://pyryco.de/setup. That URL currently redirects to the pyrycode repo README; that's fine — a real landing page is out of scope here.

Acceptance Criteria

• Tapping the Welcome screen's secondary CTA ("Set up pyrycode first") opens https://pyryco.de/setup in the device's default browser via Intent.ACTION_VIEW + Context.startActivity.
• The wiring lives at the composable(Routes.Welcome) { ... } site in MainActivity.kt (replacing the existing TODO(#14) line); WelcomeScreen's onSetup: () -> Unit parameter shape is unchanged.
• Compose @Preview functions in WelcomeScreen.kt still compile and render — preview callbacks remain no-ops, no preview-only branching needed.
• ./gradlew assembleDebug passes.
• ./gradlew lint passes.

Technical Notes

• Existing wiring shape at MainActivity.kt's onPaired shows the pattern — the architect can mirror it with a Context-aware lambda (e.g. LocalContext.current captured in the composable { ... } body).
• No new dependencies expected.
• URL is a hardcoded constant — no input parsing, not security-sensitive.

Out of Scope

• Scanner UI / behavior — owned by feat(ui): add Stub Scanner screen + route #12 (closed).
• Real pairing landing page at pyryco.de/setup — temporary redirect to repo README is acceptable.
• Hardening for the "no browser installed" edge case (ActivityNotFoundException) — defer until observed; not a realistic failure mode on stock Android 13+ where the system handles ACTION_VIEW for https URLs.

Depends on

• feat(ui): add Welcome screen scaffold (no navigation) #7 (Welcome scaffold) — closed.
• feat(ui): add Stub Scanner screen + route #12 (Scanner route exists) — closed; also delivered the onPaired → Scanner half of the original feat(ui): wire Welcome screen CTAs to Scanner navigation + external browser #14 scope.

Size Estimate

XS — single callback wiring at one call site in MainActivity.kt, well under 30 lines.

[ilmoniemi]

🤖 Product Owner — creates structured issues

po agent has completed work on this ticket.

Agent output (click to expand)

Ticket #14 refined. Key changes:

- **Scope tightened**: AC1 ("primary CTA → Scanner") removed — already delivered by PR #41 (#12). The current `MainActivity.kt` shows `onPaired → navController.navigate(Routes.Scanner)` is live; only `onSetup` is still a `TODO(#14)`. The refined ticket targets just that one callback.
- **Format normalized**: User Story / Context / Acceptance Criteria / Technical Notes / Out of Scope / Depends on / Size Estimate.
- **AC tightened to testable form**: names the call site (`composable(Routes.Welcome)` in `MainActivity.kt`), the mechanism (`Intent.ACTION_VIEW` + `Context.startActivity`), and the URL.
- **Not security-sensitive**: hardcoded constant URL, no untrusted input — label omitted per the in-doubt-apply guidance (no doubt here).
- **Size**: `size:xs` kept — single callback at one call site, well under 30 lines. Dispatcher will add `ready:po` on completion.

Ready for human review. Move to the next column when approved.