feat: TUI dashboard actions (delete, consolidate, prune, decay)

[pszymkowiak]

Summary

• Add executable actions to TUI dashboard: d (delete memory), c (consolidate topic), p (prune stale), D (apply decay)
• Confirmation dialog before all destructive actions (y/N)
• Help overlay (?) with full keybinding reference
• Version number displayed in tab title and help footer
• Context-specific status bar showing available actions per tab
• Status messages with auto-expire (5s) for action feedback
• Safe UTF-8 string truncation (fixes potential panic on multi-byte chars)
• Delete from search results via Del key
• Replace remaining ● symbol with ASCII #

Test plan

• cargo build passes
• cargo clippy -- -D warnings clean
• cargo fmt --check clean
• 152 tests pass
• Manual test: icm dashboard opens correctly
• Manual test: actions trigger confirmation dialogs
• Manual test: ? shows help overlay

[pszymkowiak]

🧞 wshm · Automated triage by AI

📊 Automated PR Analysis

✨ Type	feature
🟡 Risk	medium

Summary

Adds interactive actions to the TUI dashboard including delete, consolidate, prune, and decay operations with confirmation dialogs, a help overlay, version display, context-specific status bar, auto-expiring status messages, and fixes a potential panic on UTF-8 string truncation.

Review Checklist

• Tests present
• Breaking change
• Docs updated

---

🤖 Analyzed automatically by wshm · This is an automated analysis, not a human review.