feat(KB-057): add interactive terminal to dashboard

- Add backend terminal API with SSE streaming for real-time output
- Create useTerminal hook with command history and navigation
- Refactor TerminalModal into interactive shell component
- Update App and Header for standalone terminal button
- Add CSS styles for terminal UI (prompts, output, spinner, welcome screen)
- Update tests for new terminal behavior

.changeset/interactive-terminal.md

@@ -2,14 +2,16 @@
 "@dustinbyrne/kb": minor
 ---
 
-Add interactive terminal to dashboard
+Add interactive terminal to dashboard for executing shell commands directly in the project directory
 
-The dashboard now includes a fully interactive shell terminal where users can execute commands directly in the project's working directory. Features include:
+The dashboard now includes a fully functional shell terminal accessible via the terminal icon in the header. Features include:
 
-- Real-time command execution with output streaming via SSE
+- Real-time command output streaming via Server-Sent Events (SSE)
 - Command history with Up/Down arrow navigation
-- Support for common commands: git, npm/pnpm/yarn, ls, cat, cd, clear, etc.
-- Command validation to block dangerous operations (rm -rf /, etc.)
-- Process kill support (Ctrl+C)
-- Clear screen (Ctrl+L)
-- Terminal accessible regardless of task state
+- Keyboard shortcuts: Ctrl+C to kill process, Ctrl+L to clear screen
+- Security validation with allowlist/blocklist for commands
+- 30-second timeout for commands with automatic cleanup
+- Monospace font styling with color-coded output (stdout/stderr/exit codes)
+- Mobile-responsive design with safe area insets
+
+The terminal is always available regardless of task state, making it convenient for quick git operations, package management, or debugging without leaving the dashboard.