Fix parser bugs in check_quants, -t flag, and related functions

[khush3e]

Problem

• Sentences with two quantifiers in disjoint scopes (e.g. ∀x P(x) ∨ ∀x Q(x)) were incorrectly rejected with "Unrecognised or invalid quantifier symbol" because check_quants compared bound variables across the entire flat string with no notion of scope. Additionally, aris -t 'BAD TEXT' would exit 0 and print "Correct!" even for invalid input.

Changes

• process.c — check_quants: Replaced scope-blind O(n²) duplicate check with a scope-aware walk; uses parse_parens to bound the search to each quantifier's governing group. Disjoint scopes may now reuse variable names; nested re-binding (∀x∀x, ∀x(P∧∀x Q)) is still rejected.
• aris.c — -t flag: Changed c_ret == -1 to c_ret != 1 so parse failures (return 0) correctly exit with EXIT_FAILURE.
• process.c — check_sides_quant: Fixed init_pos >= 0 guard (always true for unsigned int) to init_pos >= (unsigned)CL, preventing an OOB read before the string when the quantifier is at position 0.
• goal.c — goal_check_line: Distinguishes AEC_MEM (-1) from parse errors (-2..-9); invalid goal text now marks the goal as unmet instead of propagating a fake memory error.
• process.c — check_conns: Added explicit j >= 1 guard before chk_str[j-1] access in the NOT-placement check.
• process.c — reverse_parse_parens: Removed a '\0' write one byte past the calloc'd buffer.