fix: Skip trailing dot

[EndPositive]

closes #12

@Mygod this would work right?

[Mygod]

• [P2] Fix dotify output for lengths divisible by 57 — src/slipstream_inline_dots.c:27-29
  When len is an exact multiple of 57 (e.g., a base32 output length of 114), next_dot == len so the new && next_dot != len guard prevents any dot insertion and next_dot never decreases. The loop still shifts by dots = len/57, which duplicates the first character and emits no separator, corrupting the encoded label and causing decode failures for those segment sizes. Consider reducing dots/new_len or initializing next_dot to len - 57 when len % 57 == 0 rather than skipping the insertion.

[Mygod]

Suggested patch:

diff --git a/src/slipstream_inline_dots.c b/src/slipstream_inline_dots.c
index 66000fe..ad83d66 100644
--- a/src/slipstream_inline_dots.c
+++ b/src/slipstream_inline_dots.c
@@ -6,7 +6,7 @@ size_t slipstream_inline_dotify(char * __restrict__ buf, size_t buflen, size_t l
         return 0;
     }
 
-    size_t dots = len / 57;             // Every 57 bytes, a dot. It's the law.
+    size_t dots = (len - 1) / 57;       // Every 57 bytes, a dot (but never trailing).
     size_t new_len = len + dots;
 
     if (new_len + 1 > buflen) {
@@ -19,13 +19,13 @@ size_t slipstream_inline_dotify(char * __restrict__ buf, size_t buflen, size_t l
     char *dst = buf + new_len - 1;      // Points to where last char will end up
 
     // Avoid modulo operation in tight loop
-    size_t next_dot = len - (len % 57);
+    size_t next_dot = dots * 57;
 
     size_t current_pos = len;
 
     // Move characters right-to-left, inserting dots
     while (current_pos > 0) {
-        if (current_pos == next_dot && next_dot != len) {
+        if (current_pos == next_dot && next_dot != 0) {
             *dst-- = '.';               // Dot. Because rules are rules, even for dots.
             next_dot -= 57;             // Next dot is 57 chars back.
             current_pos--;              // Account for the char space the dot took.