Docs: Update JavaScript programming documentation

[sensei-hacker]

Summary

Updates JavaScript programming documentation to document new features added in INAV 9.0:

• PID controller output access (pid[0-3].output)
• Flight mode detection (flight.mode.poshold, flight.mode.rth, etc.)
• Updated sticky syntax to use variable assignment pattern
• Updated version history for INAV 9.0

Changes

• docs/javascript_programming/JAVASCRIPT_PROGRAMMING_GUIDE.md - Added flight mode and PID documentation, updated sticky examples
• docs/javascript_programming/api_definitions_summary.md - Updated PID and flight mode descriptions
• docs/javascript_programming/index.md - Added new features to language support list, updated version history

Testing

Documentation changes only - no code changes.

Related

Related to configurator PR #2470