Fix CSV column header spacing in FlightDataExporter

[Copilot]

FlightDataExporter.export_data() generates CSV headers with spaces after commas (e.g., # Time (s), Vz (m/s)), causing pandas to parse column names with leading spaces (' Vz (m/s)' instead of 'Vz (m/s)').

Changes

• flight_data_exporter.py:159: Remove space after comma in header concatenation

  # Before
  exported_header += f", {variable_function.__outputs__[0]}"
  
  # After  
  exported_header += f",{variable_function.__outputs__[0]}"

• test_flight_data_exporter.py: Add test validating header format and pandas column accessibility

Impact

Before:

df = pd.read_csv("flight_data.csv")
df[' Vz (m/s)']  # Leading space required

After:

df = pd.read_csv("flight_data.csv")
df['Vz (m/s)']  # No leading space

Aligns general path behavior with fast path (lines 104-115), which already uses comma-only formatting.

Fixes #864

Original prompt

solve issue #864

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[Copilot]

Pull Request Overview

This PR fixes CSV export headers to remove leading spaces after commas, making column names more accessible when reading with pandas (addresses Issue #864).

• Removed space after comma in CSV header generation for the general export path
• Added comprehensive test to validate CSV column headers have no leading spaces

Reviewed Changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
rocketpy/simulation/flight_data_exporter.py	Removed space after comma in header string concatenation for custom variable exports
tests/unit/test_flight_data_exporter.py	Added test to verify CSV headers don't contain leading spaces and are pandas-compatible

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.28%. Comparing base (9cf3dd4) to head (b4aef19).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #865   +/-   ##
========================================
  Coverage    80.27%   80.28%           
========================================
  Files          104      104           
  Lines        12769    12769           
========================================
+ Hits         10250    10251    +1     
+ Misses        2519     2518    -1     

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[Copilot]

Pull Request Overview

Copilot reviewed 1 out of 2 changed files in this pull request and generated no new comments.