UI-A2 — Adopt motion tokens across widgets

[ZhuchkaTriplesix]

Epic: #170
Depends on: #173 (UI-A1)

Source: docs/motion-and-high-refresh.md §2

Goal

Replace scattered magic Duration(...) and Curves.easeOut literals with QueryaMotion tokens. No visual redesign yet — unify timing only.

Files (audit from research)

• lib/shared/widgets/app_dialog.dart
• lib/shared/widgets/querya_dropdown.dart (+ querya_dropdown_tokens.dart)
• lib/features/settings/theme_picker_button.dart
• lib/features/main_screen/workspace_panel.dart
• lib/features/connections/connections_panel_pg_tree.dart
• lib/features/connections/connections_panel_{sidebar,mysql,mongo,redis,postgres_connection}.dart
• lib/features/{mysql,postgresql}/*_workspace_home.dart
• lib/features/connections/new_connection_dialog.dart

Implementation

• Import QueryaMotion; replace hardcoded 100/120/200 ms with fast / standard as appropriate.
• Replace Curves.easeOut with QueryaMotion.enter or standard per interaction type.
• Keep tooltip waitDuration values unchanged (not motion tokens).
• Do not add new animations in this issue (that's UI-A3).

Acceptance Criteria

• No magic animation Duration(milliseconds: …) left in scoped files (except debounce/poll intervals).
• Existing layout/overflow tests stay green.
• flutter analyze clean.

Tests

• Re-run affected widget/layout tests; no geometry changes.

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