rename ckpts stock_{16f,32f}_10pct -> baseline_* (naming consistency)

Reorg: move 16f stock/v9_1 ckpts into S2 stage-first tree (drop machine name, tag 16f)

Add 4B 32f inference ckpt under stage-first ckpts/ -> ckpts/S2/4b/qwen3_5_2b/stock_32f_10pct/v0-20260606-044138/checkpoint-785

Add 4B 32f inference ckpt under stage-first ckpts/ -> ckpts/S2/4b/qwen3_5_2b/v10_2_32f_10pct/v0-20260610-154054/checkpoint-785