fix(postprocess): trim adjacent word overlap

Remove residual one-word suffix-prefix carry-over between adjacent caption segments so reprocessed transcripts no longer repeat bridge words across lines.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/lib/server/postprocess.ts

@@ -42,7 +42,7 @@ function mergeConsecutive(segments: Segment[]): Segment[] {
 const MAX_CHAIN_GAP_SECS = 0.15;
 const MIN_MEANINGFUL_WORDS = 2;
 const MIN_MEANINGFUL_CHARS = 8;
-const MIN_OVERLAP_WORDS = 3;
+const MIN_OVERLAP_WORDS = 1;
 
 function splitWords(text: string): string[] {
 	return text.trim().split(/\s+/).filter(Boolean);