refactor: Extract common Data1D processing logic from sync modifiers

[andeplane]

Problem

The three sync modifiers (synccomputesmodifier.ts, syncfixesmodifier.ts, syncvariablesmodifier.ts) have ~80% code duplication, specifically in the Data1D processing logic (lines ~55-118 in each file).

Current Behavior

Each modifier contains nearly identical code for:

• Getting data1DNames and checking size
• Processing clearPerSync logic
• Looping through data1DVector and extracting x/y values
• Proper cleanup of WASM objects (data1DNamesWrapper, lmpData, data1DVector)

Expected Behavior

Extract the common Data1D processing logic into a shared helper function that can be reused by all three modifiers.

Proposed Solution

Create a shared helper function in src/modifiers/modifier.ts (or a new utility file):

function processData1D(
  modifier: LMPModifier,
  data1D: Data1D | undefined,
  input: ModifierInput,
  everything: boolean,
  syncDataPoints: boolean
): Data1D | undefined

This function should handle:

1. Getting data1DNames wrapper and extracting size
2. Checking if data1D needs to be created
3. Processing clearPerSync logic
4. Looping through data1DVector and extracting x/y values from WASM memory
5. Proper cleanup of all WASM objects
6. Returning the processed data1D object

Files to Modify

• src/modifiers/modifier.ts (add helper function)
• OR create new utility file if preferred

Benefits

• Reduces code duplication (~125 lines per file → ~50-60 lines)
• Makes maintenance easier (fix bugs/improvements in one place)
• Ensures consistent WASM memory cleanup
• Easier to add new modifiers in the future

Related

This is a prerequisite for issue #183 (memory leak fixes) and will make future improvements easier. Should be done after basic memory leak fixes.