feat(app): map tab — locate + nearby flags + tap-to-pick (v0.9.0)

Adds a 지도 tab (Leaflet + OSM, no API key needed):
- "📍 내 위치" centers on GPS.
- nearby spots render as teal flags (those in the current viewport, capped
  300 for perf) from the 1,553 locations; tapping a flag loads that spot's
  tide immediately.
- tapping anywhere on the map drops a pin + shows "📍 이 위치 조석 보기"
  to use that arbitrary coordinate (reuses the model-tide path) — avoids
  accidental navigation on pan.
- TabBar now 5 tabs (icons 34→29px); map z-index isolated so the sticky
  search bar stays on top.
- Also: North Korea points (원산·청진) removed from the dataset → 1,553.

Verified on mobile viewport: OSM tiles + flags around 군산, locate button,
bottom hint, search bar unobstructed. Deployed v0.9.0.

Constraint: OSM tiles for now (no key); fine at this volume — swap to Kakao/Naver tiles later if branding/coverage needs it. Flags limited to viewport (300) so the full 1,553 don't render at once.
Confidence: high
Scope-risk: module
Reversibility: trivial
Directive: Consider Kakao Map JS tiles (Korean labels, port detail) if OSM coverage feels thin; needs a JS key + domain whitelist.
Tested: build clean; APK deployed; Playwright shows working map, flags, controls; tide path unchanged.
Not-tested: on-device GPS centering + marker tap; tile load on cellular.
Related: docs/BACKLOG.md

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