Fix: Correct problematic string in SystemMessageEntryPreferences

The guide string for the "Chromium-based Browser" default entry
contained a sequence `\"-\"` which caused a Kotlin compiler error
(unresolved reference, receiver type mismatch for minus operator)
during release builds.

This commit changes the problematic sequence
`tap the \"-\" (multiple times)`
to
`tap the 'minus' symbol (multiple times)`
to avoid the parsing issue and allow the build to complete successfully.
The meaning of the guide text remains the same for you.

Author: google-labs-jules[bot]

app/src/main/kotlin/com/google/ai/sample/util/SystemMessageEntryPreferences.kt

@@ -44,7 +44,7 @@ object SystemMessageEntryPreferences {
                     ),
                     SystemMessageEntry(
                         title = "Chromium-based Browser",
-                        guide = "//To see more in a screenshot, you may want to consider zooming out. To do this, tap the three vertical dots, select the appropriate location in the menu, and then tap the "-" (multiple times). You can only zoom out to 50%.\""
+                        guide = "//To see more in a screenshot, you may want to consider zooming out. To do this, tap the three vertical dots, select the appropriate location in the menu, and then tap the 'minus' symbol (multiple times). You can only zoom out to 50%.\""
                     )
                 )
                 saveEntries(context, defaultEntries) // This saves them to KEY_SYSTEM_MESSAGE_ENTRIES