Optimize and simplify loops, table lookups, and branchless parsers

- Replace sequential colon-counting loop with branchless CTZ bitmask in src/pen.h
- Replace linear strchr with 256-bit ASCII punctuation bitmask in src/selection.c
- Flatten 3D color cube loop and precompute constants in src/palette.c
- Use static 256-byte LUT for hex decoding and bsearch for termcap in src/escape.c
- Replace capacity doubling while loops with branchless CLZ pow2 helpers across core
- Use direct memset/memcpy in src/snapshot.c
- Optimize input digit/byte formatting, alt-prefix path, and make keyboard state optional in src/input.c

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/input_test.c b/tests/input_test.c
index 6ee2caa..1a44f42 100644
--- a/tests/input_test.c
+++ b/tests/input_test.c
@@ -101,9 +101,22 @@ int main(void)
     typed('b', TERM_MOD_ALT | TERM_MOD_CTRL); expect("\033\002");
     K(.key = TERM_KEY_BACKSPACE, .mods = TERM_MOD_ALT); expect("\033\177");
     K(.key = TERM_KEY_RETURN, .mods = TERM_MOD_ALT); expect("\033\r");
+    K(.key = TERM_KEY_TAB, .mods = TERM_MOD_ALT); expect("\033\t");
+    K(.key = TERM_KEY_TAB, .mods = TERM_MOD_ALT | TERM_MOD_SHIFT); expect("\033[Z");
+    K(.key = TERM_KEY_ESCAPE, .mods = TERM_MOD_ALT); expect("\033");
 
     K(.key = TERM_KEY_LEFT, .mods = TERM_MOD_ALT); expect("\033[1;3D");
 
+    {
+        char b_null[16];
+        struct term_input_result r = term_input_encode_key(
+            NULL,
+            &(struct term_key_event){ .key = TERM_KEY_UP, .action = TERM_KEY_PRESS },
+            &(struct term_modes){0},
+            b_null, sizeof(b_null));
+        assert(r.status == TERM_INPUT_BYTES && r.len == 3 && !memcmp(b_null, "\033[A", 3));
+    }
+
     K(.codepoint = 'b', .base = 'b', .text = 0x222B, .text_deferred = true);
     expect("");