chore: add increment/decrement operators and test suite to parser and tokenizer

Implement prefix and postfix ++/-- operators in the tokenizer (Inc/Dec token types) and parser (factor/unary functions) with correct pre/post semantics. Add increment_decrement_test.rc covering all four operator forms. Update Makefile to include the new test file in TESTS, add run-increment-decrement-test target, and fix .PHONY and TARGET dependency on dirs.

src/parser.c

@@ -119,6 +119,17 @@ long factor() {
 
             Symbol *sym = &locals[idx];
 
+            if (pc < MAX_TOK && (tokens[pc].type == Inc || tokens[pc].type == Dec)) {
+                long val = memory[sym->addr];
+                if (tokens[pc].type == Inc) {
+                    memory[sym->addr]++;
+                } else {
+                    memory[sym->addr]--;
+                }
+                pc++;
+                return val;
+            }
+
             if (pc >= MAX_TOK) return 0;
             if (tokens[pc].type == '[') {
                 pc++;
@@ -158,6 +169,21 @@ long factor() {
 
 long unary() {
     if (pc >= MAX_TOK) return 0;
+    if (tokens[pc].type == Inc || tokens[pc].type == Dec) {
+        int op = tokens[pc++].type;
+        Token *t = &tokens[pc];
+        if (t->type != Id) error("Expected identifier after ++/--");
+        int idx = find_local(t->text, t->val);
+        if (idx == -1) error("Undefined variable");
+        pc++;
+        long addr = locals[idx].addr;
+        if (op == Inc) {
+            memory[addr]++;
+        } else {
+            memory[addr]--;
+        }
+        return memory[addr];
+    }
     if (tokens[pc].type == '*') {
         pc++;
         int addr = unary();

src/tokenizer.c

@@ -77,6 +77,8 @@ void tokenize(char *src) {
         if (!strncmp(s, ">=", 2)) { t->type = Ge; s += 2; continue; }
         if (!strncmp(s, "&&", 2)) { t->type = And; s += 2; continue; }
         if (!strncmp(s, "||", 2)) { t->type = Or; s += 2; continue; }
+        if (!strncmp(s, "++", 2)) { t->type = Inc; s += 2; continue; }
+        if (!strncmp(s, "--", 2)) { t->type = Dec; s += 2; continue; }
 
         if (*s == '<') { t->type = Lt; s++; continue; }
         if (*s == '>') { t->type = Gt; s++; continue; }

src/types.h

@@ -9,7 +9,7 @@
 
 enum {
     Num = 128, Str, Id, Int, Char, Else, If, While, Return, Printf,
-    Assign, Eq, Ne, Lt, Gt, Le, Ge, Or, And
+    Assign, Eq, Ne, Lt, Gt, Le, Ge, Or, And, Inc, Dec
 };
 
 typedef struct {