Fix date parsing mismatch when pasting outside edit mode

[radheshpai87]

Fixes #5059

This PR fixes inconsistent date/time parsing when pasting values into cells. Previously, pasted dates were parsed by the server using its locale settings, often resulting in dates different from what the user entered.

Technical details

Applied the existing DateTimeFormatter system (already used in edit mode) to the paste flow. Now when users paste date/time values into cells with custom format metadata (e.g., European date format), the frontend parses them correctly before sending to the backend.

Changes made to /src/components/sheet/clipboard/paste.ts:

1. Added imports:

   • getColumnMetadataValue from @mathesar/api/rpc/columns to read column format settings
   • DateTimeFormatter and DateTimeSpecification from @mathesar/utils/date-time to parse dates

2. Created parseDateTimeValue() helper:

   • Detects if column is date/datetime/time type
   • Reads column metadata (date_format, time_format)
   • Uses DateTimeFormatter to parse pasted value respecting those settings
   • Returns canonical ISO format to backend

3. Updated prepareStructuredCellValue():

   • Detects date/datetime/time columns
   • Routes pasted values through new parser
   • Gracefully falls back to raw value if parsing fails

Screenshots

• Before

• After (Now after pasting it shows like this)

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the develop branch of the repository
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I tried running the project locally and verified that there are no
  visible errors.

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