fix(rcwt): Fix timestamp calculation for RCWT/BIN format files

The rcwt_loop() function set min_pts = 0 for RCWT files but did not
set pts_set = 2 (MinPtsSet). This caused the Rust timing code to skip
the fts_now calculation (which checks pts_set == MinPtsSet), resulting
in all captions having timestamps compressed near 0 instead of their
correct times spread across the file duration.

The fix adds pts_set = 2 after setting min_pts, which tells the timing
system that min_pts is valid and fts_now can be calculated properly.

Fixes Test 217 timing issue where:
- Before: 00:00:00,001 --> 00:00:00,091 (wrong)
- After:  00:00:02,402 --> 00:00:04,536 (correct)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: cfsmp3

src/lib_ccx/general_loop.c

@@ -1392,9 +1392,12 @@ int rcwt_loop(struct lib_ccx_ctx *ctx)
 	dec_sub = &dec_ctx->dec_sub;
 	telctx = dec_ctx->private_data;
 
-	/* Set minimum and current pts since rcwt has correct time */
+	/* Set minimum and current pts since rcwt has correct time.
+	 * Also set pts_set = 2 (MinPtsSet) so the Rust timing code knows
+	 * that min_pts is valid and can calculate fts_now properly. */
 	dec_ctx->timing->min_pts = 0;
 	dec_ctx->timing->current_pts = 0;
+	dec_ctx->timing->pts_set = 2; // 2 = min_pts set
 
 	// Loop until no more data is found
 	while (1)