fw/services/persist: raise per-app storage limit to 1 MiB

Raise the per-app persistent storage limit from 6 KiB to 1 MiB. Modern
Pebble watches have 32 MB of flash storage, so a 1 MiB per-app limit is
reasonable. Update the API documentation accordingly.

Fixes #416

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Gerard Marull-Paretas <gerard@teslabs.com>
Signed-off-by: Joshua Jun <lets@throw.rocks>

Author: 2 people

src/fw/applib/persist.h

@@ -35,7 +35,7 @@
 //! retrieve values from the phone, it provides you with a much faster way to restore state.
 //! In addition, it draws less power from the battery.
 //!
-//! Note that the size of all persisted values cannot exceed 4K per app.
+//! Note that the size of all persisted values cannot exceed 1MB per app.
 //!   @{
 
 //! The maximum size of a persist value in bytes

src/fw/services/persist/service.c

@@ -19,7 +19,7 @@
 #include "util/list.h"
 #include "util/units.h"
 
-#define PERSIST_STORAGE_MAX_SPACE KiBYTES(6)
+#define PERSIST_STORAGE_MAX_SPACE MiBYTES(1)
 #define PERSIST_STORAGE_INITIAL_ALLOC KiBYTES(4)
 
 typedef struct PersistStore {