Address minor review comments on multi-process core

- Darwin notification name prefix com.powersync.changes (was co.).
- Simplify the changelog entry to one feature bullet, dropping the
  internal-only details.
- Document that only the main app should call connect(); extensions can
  read and write the shared database but must not open a second sync
  connection.

Author: asiergmorato

CHANGELOG.md

@@ -4,18 +4,8 @@
 
 * `PowerSyncDatabase(dbFilename:)` now accepts an absolute path (starting with `/`), used
   as-is so the database can live in an App Group container shared with app extensions.
-  Plain filenames keep the existing behavior, and `close(deleteDatabase: true)` deletes the
-  files at the absolute location.
-* Opening the connection pool retries while another process holds the database. The
-  `pragma journal_mode = WAL` transition reports `SQLITE_BUSY`/`SQLITE_BUSY_RECOVERY`
-  without consulting the busy handler, so concurrent cold opens (an app launching while its
-  extension opens the same file) used to fail; the pool now retries with backoff.
-* Added an opt-in cross-process change signal: each pool posts a Darwin notification after
-  every committed write and, on receipt, re-emits `tableUpdates` with
-  `EXTERNAL_CHANGES_MARKER` so `watch` queries and the upload client wake for writes made by
-  other processes sharing the database file. Only databases opened from an absolute path
-  (an App Group container) use the signal; in-memory and default-directory databases skip
-  it, since they can't be shared across processes.
+  Plain filenames keep the existing behavior. The SDK coordinates opening the database to
+  avoid conflicts and can share update notifications across the main app and extensions.
 
 ## 1.14.3
 

Sources/PowerSync/Implementation/CrossProcessChangeSignal.swift

@@ -24,7 +24,7 @@ final class CrossProcessChangeSignal: @unchecked Sendable {
     init(databasePath: String, logger: any LoggerProtocol) {
         // Stable across processes: both sides derive the name from the canonical path.
         let canonical = URL(fileURLWithPath: databasePath).standardizedFileURL.path
-        self.name = "co.powersync.changes.\(Self.fnv1a(canonical))"
+        self.name = "com.powersync.changes.\(Self.fnv1a(canonical))"
         self.logger = logger
     }
 

Sources/PowerSync/PowerSyncDatabase.swift

@@ -9,7 +9,10 @@ public let DEFAULT_DB_FILENAME = "powersync.db"
 ///   - dbFilename: The database filename. Defaults to "powersync.db". Plain names are
 ///     stored in the default databases directory; an absolute path (starting with "/") is
 ///     used as-is, which allows sharing the database with app extensions through an App
-///     Group container.
+///     Group container. The database itself can be used concurrently from the main app and
+///     its extensions, but only the main app should call `connect`. Two sync connections on
+///     the same database waste resources and are untested (and could corrupt the sync
+///     client); let extensions read and write, and leave syncing to the app.
 ///   - logger: Optional logging interface
 ///   - initialStatements: An optional list of statements to run as the database is opened.
 /// - Returns: A configured PowerSyncDatabase instance