okf v0.3.5 — scale guardrails, Windows fix, validator tests

Fixed

• validate/visualize: no longer crash with UnicodeEncodeError on default Windows consoles (cp1252) — stdout/stderr are reconfigured to UTF-8. Thanks @crackcode09 (#3). A cp1252 regression step now runs in CI.
• visualize: large bundles no longer freeze the browser — the force (cose) layout applies only up to 1,000 concepts (measured ~32 s of blocked main thread at ~2k), larger bundles default to the linear concentric layout; explicit --layout cose still wins. Thanks @td-bl (#4, #5).
• visualize: filter passes wrapped in cy.batch(), search box debounced (150 ms).

Added

• Unit tests for okf_validate.py internals — 25 cases, stdlib unittest, in CI (#1).
• visualize: warning above 5,000 concepts + --max-nodes N to refuse oversized bundles in CI.
• Decision record: scale guardrails.

Full Changelog: okf--v0.3.3...okf--v0.3.5