Remove LocationNotesCounter for privacy-first approach (#820)

Simplifies geonotes architecture by eliminating all background subscriptions:

- Delete LocationNotesCounter.swift (104 lines) and related tests (58 lines)
- Remove background subscription system entirely
- Icon is now constant darker orange (indicates availability, not state)
- Subscription ONLY happens when user explicitly opens the sheet
- Total: ~220 lines of code removed

Privacy Benefits:
- Zero network traffic until user action
- No location leaking to relays via background polling
- User must explicitly opt-in to discover notes

The icon (note.text in orange) simply indicates the feature is available
when location permission is granted. Notes are only fetched when the
sheet is opened, prioritizing privacy over convenience.

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchatTests/LocationNotesManagerTests.swift

@@ -91,61 +91,3 @@ struct LocationNotesManagerTests {
         case shouldNotDerive
     }
 }
-
-@MainActor
-struct LocationNotesCounterTests {
-    @Test func subscribeWithoutRelaysMarksUnavailable() {
-        var subscribeCalled = false
-        let deps = LocationNotesCounterDependencies(
-            relayLookup: { _, _ in [] },
-            subscribe: { _, _, _, _, _ in subscribeCalled = true },
-            unsubscribe: { _ in }
-        )
-
-        let counter = LocationNotesCounter(testDependencies: deps)
-        counter.subscribe(geohash: "u4pruydq")
-
-        #expect(!subscribeCalled)
-        #expect(!counter.relayAvailable)
-        #expect(counter.initialLoadComplete)
-        #expect(counter.count == 0)
-    }
-
-    @Test func subscribeCountsUniqueNotes() {
-        var storedHandler: ((NostrEvent) -> Void)?
-        var storedEOSE: (() -> Void)?
-        let deps = LocationNotesCounterDependencies(
-            relayLookup: { _, _ in ["wss://relay.geo"] },
-            subscribe: { filter, id, relays, handler, eose in
-                #expect(relays == ["wss://relay.geo"])
-                #expect(filter.kinds == [1])
-                #expect(!id.isEmpty)
-                storedHandler = handler
-                storedEOSE = eose
-            },
-            unsubscribe: { _ in }
-        )
-
-        let counter = LocationNotesCounter(testDependencies: deps)
-        counter.subscribe(geohash: "u4pruydq")
-
-        var first = NostrEvent(
-            pubkey: "pub",
-            createdAt: Date(),
-            kind: .textNote,
-            tags: [["g", "u4pruydq"]],
-            content: "a"
-        )
-        first.id = "eventA"
-        storedHandler?(first)
-
-        let duplicate = first
-        storedHandler?(duplicate)
-
-        storedEOSE?()
-
-        #expect(counter.relayAvailable)
-        #expect(counter.count == 1)
-        #expect(counter.initialLoadComplete)
-    }
-}