docs: clarify Claro v1 status and validation

docs/PERFORMANCE.md

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+# Claro Performance and Optimization Notes
+
+Current release: **Claro v1.18.26**
+
+Performance work should come after language behavior is stable and measured. Do not optimize blindly.
+
+## Current priority
+
+Claro's current priority is correctness, accessibility, friendly diagnostics, and reliable beginner examples.
+
+## Before optimization work
+
+Add:
+- small benchmark scripts
+- expected-output checks for benchmark examples
+- a timing command or repeatable timing script
+- documentation for what is being measured
+
+## Optimization rules
+
+- Keep beginner-visible behavior unchanged.
+- Measure before and after every optimization.
+- Prefer simple interpreter cleanup before complex compiler architecture.
+- Do not add bytecode, JIT, or advanced compiler stages until the v1 semantics are stable.
+
+See also:
+- `ROADMAP.md`
+- `CURRENT_STATUS.md`
+- `FUTURE_FEATURES_ROADMAP.md`