Feature: Multi-Region Selection

[yimsk]

Multi-Region Selection 🌍

Enable selecting multiple regions in the Region selector (R key) for simultaneous querying.

Current Behavior

• R key opens region list
• Single selection only
• Switches to selected region

Proposed Behavior

┌ Select Regions ────────────────────┐
│ ☑ us-east-1      (N. Virginia)     │
│ ☐ us-east-2      (Ohio)            │
│ ☐ us-west-1      (N. California)   │
│ ☐ us-west-2      (Oregon)          │
│ ☑ ap-northeast-1 (Tokyo)           │
└────────────────────────────────────┘
Space: Toggle | Enter: Apply | a: All | n: None

Features

1. Multi-select UI: Space to toggle, checkboxes
2. Parallel Fetch: Query selected regions concurrently
3. Region Column: Add Region column to resource lists (末尾、マルチリージョン時のみ)
4. Error Handling: Show successful results + notify errors for failed regions

UX Flow

1. Press R → Region selector opens
2. Space to toggle regions (multi-select)
3. Enter to apply
4. Resources from all selected regions displayed with Region column

Implementation Tasks

• RegionSelector: single → multi-select UI
• App state: region string → regions []string
• DAO: parallel fetch across regions
• Render: add Region column (conditional)
• Error handling: partial failure support

Notes

• Global services (IAM, Route53, CloudFront): work as current (single region)
• Startup behavior: unchanged (single region from profile default)

Related

• Feature: Multi-Profile Selection #49 Multi-Profile Selection (similar pattern, implement after this)
• Feature: Persist Region/Profile Selection to Config #50 Persist Region/Profile Selection (config persistence)

[yimsk]

Implemented in #53