feat: add functions support, agent improvements, and explorer live reload

[cristipufu]

Summary

• Functions documentation: Add coded functions support across skills (SKILL.md, creating-functions.md, creating-agents.md, running-agents.md) with uipath.json, bindings.json, and pack/publish workflow
• Evaluations fix: Document evaluator file creation as explicit prerequisite step — eval sets fail without evaluator files
• Explorer live reload: Sidebar file tree now re-fetches directory listings on files.changed WebSocket events (new/deleted files appear immediately)
• Agent bash UTF-8: Fix UnicodeDecodeError on Windows by setting PYTHONUTF8=1 + encoding="utf-8" on subprocess calls
• Agent system prompt: Add full build cycle instructions (code → init → evaluations → run evals), force bash tool usage over manual instructions
• UI: Remove em dash from reload toast
• Version: Bump to 0.0.62

Test plan

• Verify explorer sidebar updates when files are added/deleted on disk
• Verify agent uses bash tool to run commands instead of giving manual instructions
• Verify agent creates evaluator files alongside eval sets
• Verify no UTF-8 decode errors when agent runs bash commands with non-ASCII output on Windows
• Verify reload toast shows "Files changed, reload to apply" (no em dash)

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