[bug] Tcl: func_start regex misses procs with nested braces in args

[squid-protocol]

During a sweep of the tri-comparison ledger, we found that the Tcl func_start regex fails to extract procedures when their argument lists contain nested braces.

Example from sqlite/tester.tcl:

proc drop_all_tables {{db db}} {

Tree-sitter and Ctags correctly extract this, but GitGalaxy's regex fails to balance or tolerate the inner braces. This causes valid proc definitions to be dropped.