Add Deck browsing feature with controller, UI, routing, and format helpers

[ercmine]

Motivation

• Introduce a swipable "Deck" experience to browse session suggestions and integrate it into existing sessions flows.
• Provide client-side telemetry and location-aware fetching for deck results and a small set of UI helper formatters.

Description

• Added a full Deck feature including state (deck_state.dart), controller (deck_controller.dart) with telemetry, location and repository integration, and a new route at /sessions/:id/deck wired into router.dart and session_page.dart.
• Implemented the Deck UI in deck_page.dart and a set of widgets for cards and details (deck_card.dart, deck_card_skeleton.dart, deck_actions_bar.dart, card_details_sheet.dart, and several small badges/pills), and hooked link launching into existing linkLauncherProvider usage.
• Registered a deckControllerProvider in providers/app_providers.dart, added format helpers in core/format/formatters.dart, and updated pubspec.yaml to include flutter_card_swiper, cached_network_image, and collection dependencies.
• Added UI behaviors such as loading/fallback states, undo stack, batching/merge logic for plans, and telemetry enqueue/flush calls to the existing telemetry repository API.

Testing

• Ran flutter analyze to ensure static analysis and imports are correct and it completed successfully.
• Ran flutter test and unit/widget tests completed successfully (no failing tests).

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Serialize telemetry flushes per session

Each call to _enqueueTelemetry starts repo.flush(...) in a detached then block, so rapid interactions can run multiple flushes concurrently for the same session. TelemetryRepository.flush mutates a shared queue (removeRange in a loop), so overlapping flushes can send duplicate batches and then fail mid-drain when one flush removes items the other still expects, which makes analytics inaccurate under normal swipe/open bursts.

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