Located posts: local only, rounded, matched against their own radius

A post given a latitude and longitude becomes LocalGeo: its position is
rounded to two decimals (about a kilometre) and stored as a 2dsphere
point, its radius clamped to 1-50 km, and it is local only - no Create,
no delivery, no outbox, never in the Mastodon API or on a profile page.
/clientapi/post/nearby takes the viewer's position for the query only
(it is neither stored nor logged), runs $geoNear and keeps posts within
each post's own radius, minus authors the viewer blocks or mutes. A
located post cannot be direct or in a group.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

PrivaPub/Controllers/ClientToServer/PostController.cs

@@ -32,6 +32,10 @@ namespace PrivaPub.Controllers.ClientToServer
 		public async Task<IActionResult> Insert(InsertPostForm form, CancellationToken token) =>
 			!ModelState.IsValid ? Invalid() : Answer(await _postsService.InsertPost(User.GetUserId(), form, token));
 
+		[HttpGet, Route("/clientapi/post/nearby")]
+		public async Task<IActionResult> Nearby([FromQuery] string avatarId, [FromQuery] double latitude, [FromQuery] double longitude, CancellationToken token) =>
+			Answer(await _postsService.Nearby(User.GetUserId(), avatarId, latitude, longitude, token));
+
 		[HttpPost, Route("/clientapi/post/update")]
 		public async Task<IActionResult> Update(UpdatePostForm form, CancellationToken token) =>
 			!ModelState.IsValid ? Invalid() : Answer(await _postsService.UpdatePost(User.GetUserId(), form, token));