fix(functions): add get_functions route and fix wrong endpoint call

[alikhere]

PR Description

The Functions panel was calling /get_locals (which runs info locals in GDB — local variables of the current stack frame) instead of an endpoint that actually returns program functions. The panel was showing wrong data on every refresh, and there was no /get_functions route on the backend at all.

Three files changed, all following existing patterns:

• Added POST /get_functions to main.py running info functions via GDB, same structure as every other route in the file
• Added test_get_functions to flask_test.py — backend test count goes from 20 to 21
• Fixed Functions.jsx to call /get_functions instead of /get_locals

How to test

Start a debug session with a compiled program, open the Functions panel and trigger a refresh.

• Before: panel received output from info locals (local variable data)
• After: panel receives output from info functions (program function list)

To verify the backend route directly:

curl -X POST http://127.0.0.1:10000/get_functions \
  -H 'Content-Type: application/json' \
  -d '{"name": "program"}'

Backend tests:

cd gdbui_server && python -m unittest discover -s tests
# 21 passed

Related Issue

Fixes #200