v0.3.0 — Kotlin support + experimental model swap

v0.3.0 — Kotlin support + experimental model swap

• Kotlin first-class support (AST chunking + dependency graph), plus
  dotted-import false-positive fix affecting Kotlin/Java/Python
  (PR #1 by @clroot)
• New SEMBLE_MODEL_PATH env var: point the encoder at a local model2vec
  output directory to swap in any distilled embedding without recompiling
• README: 50-query ground-truth eval published for the default model
  (R@1 70%, R@5 98%, R@10 100%, Korean R@5 80%) + guidance on which
  CoIR teachers to consider for further distillation