Harden public intake bounds against untrusted growth (#1451)

* Bound public rate-limit buckets against attacker-keyed growth.

Keep the NIP-13 PoW sender bypass, skip content-bucket minting on
sender reject, and evict idle/oldest entries at a hard cap.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Stop Cashu-looking text from skipping long-message guards.

Oversized public content always collapses and takes the plain
formatting path so remote tokens cannot force layout/regex DoS.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Cap teleported geohash participant markers.

Bound the set with FIFO eviction, clear it on channel switch, and
prune markers that leave the visible participant list.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Bound untrusted Nostr relay frames and event tags.

Reject oversized inbound messages before JSON parse, cap tag
arrays/values at decode, and stop logging raw tag contents.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Fail soft when Noise handshake state is unexpectedly missing.

Replace the initiator startHandshake force unwrap with a guard
that throws invalidState instead of crashing.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Cap geohash nickname cache from remote Nostr events.

FIFO-evict at capacity, clear on channel switch, and prune
nicknames that leave the visible participant list.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Avoid overlapping exclusive access in the rate limiter.

Make bucket helpers static so inout dictionary updates do not
conflict with a mutating call on self.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Fix rate-limiter tests for mutating allow under #expect.

Call allow outside the macro so Swift Testing does not capture an
immutable copy of the struct.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Drop unused WebSocket data helper; reset rate limiter on panic wipe.

dataWithinInboundLimit replaced the unbounded path, and panic clear
should not leave public intake buckets behind.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

bitchat/ViewModels/NostrInboundPipeline.swift

@@ -196,7 +196,10 @@ final class NostrInboundPipeline {
         // Sampled: fires for every geo event and floods dev logs in busy geohashes.
         geoEventLogCount += 1
         if geoEventLogCount == 1 || geoEventLogCount.isMultiple(of: TransportConfig.nostrInboundEventLogInterval) {
-            SecureLogger.debug("GeoTeleport: recv #\(geoEventLogCount) pub=\(event.pubkey.prefix(8))… pow=\(powBits) tags=\(event.tags.map { "[" + $0.joined(separator: ",") + "]" }.joined(separator: ","))", category: .session)
+            SecureLogger.debug(
+                "GeoTeleport: recv #\(geoEventLogCount) pub=\(event.pubkey.prefix(8))… pow=\(powBits) tagCount=\(event.tags.count)",
+                category: .session
+            )
         }
 
         if context.isNostrBlocked(pubkeyHexLowercased: event.pubkey) {