Added “Date Added” Field for Food Items#320

[gurnoorpannu]

Fixes #320

Changes Made

• Added dateAdded field to ExpirationDate entity with automatic timestamp
• Created database migration (v3 → v4) with backward compatibility for existing items
• Updated UI to display "Added on [date]" in food cards (subtle, small text)
• Added read-only "Date Added" field in edit screen for existing items
• Updated CSV export/import to handle new field with backward compatibility
• Updated preview data and string resources

[lorenzovngl]

Hi, I think it’s a great implementation. I requested a few changes, and I’d also like to suggest making this feature optional, allowing users to choose whether to display the added date for items, as shown in the image below.

Here's a starting code:

        SettingsItem(
            label = "Show added date",
            description = "Display the date when each item was added to your list."
        ) {
            Row(
                verticalAlignment = Alignment.CenterVertically,
                modifier = Modifier.padding(start = 11.dp)
            ) {
                Switch(
                    modifier = Modifier.padding(start = 4.dp),
                    checked = isAddedDateEnabled,
                    onCheckedChange = { enabled ->
                        // Logic
                    }
                )
            }
        }

[lorenzovngl]

Better to remove these lines, otherwise the appearance of the textfield doesn't clearly tell to the user that it's disabled.

[lorenzovngl]

Could you please add some unit tests for this migration here?