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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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Serialize telemetry flushes per session

Each telemetry event starts a fire-and-forget repo.flush(...) via .then, so rapid interactions (multiple swipes/taps in quick succession) can run TelemetryRepository.flush concurrently on the same in-memory queue. Because flush removes ranges after awaiting network I/O, overlapping flushes can remove stale indices, causing dropped/duplicated events or RangeError at runtime; this corrupts deck telemetry under normal user behavior.

Useful? React with 👍 / 👎.

[chatgpt-codex-connector]

Clear undo state when refreshing deck data

Refreshing only resets loading flags and plans, but leaves undoStack (and shown-card history) intact. After a retry/refresh, the Undo button can still restore cards from the previous batch into the newly fetched deck, mixing stale suggestions with current results and skewing subsequent swipe flow/telemetry.

Useful? React with 👍 / 👎.