feat(daemon): add daemon mode with C&C and display abstraction

- Add display abstraction with swappable backends (TerminalDisplay, NullDisplay)
- Separate C&C into RX/TX topics for serial-like communication
- Add StreamController with automatic ntfy topic warmup
- Add performance monitoring for render + display stages
- Update AGENTS.md and README.md with daemon/cmd operating procedures
- Add clean/clobber tasks to mise.toml
- Add tests for display, effects controller, and controller warmup
- Fix bug where /effects reorder command was unreachable

AGENTS.md

@@ -22,13 +22,37 @@ uv sync
 ### Available Commands
 
 ```bash
+# Development
 mise run test       # Run tests
 mise run test-v     # Run tests verbose
 mise run test-cov   # Run tests with coverage report
 mise run lint       # Run ruff linter
 mise run lint-fix   # Run ruff with auto-fix
 mise run format     # Run ruff formatter
-mise run ci         # Full CI pipeline (sync + test + coverage)
+mise run ci         # Full CI pipeline
+
+# Runtime
+mise run run        # Interactive terminal mode (news)
+mise run run-poetry # Interactive terminal mode (poetry)
+mise run run-firehose # Dense headline mode
+
+# Daemon mode (recommended for long-running)
+mise run daemon         # Start mainline in background
+mise run daemon-stop    # Stop daemon
+mise run daemon-restart # Restart daemon
+
+# Command & Control
+mise run cmd           # Interactive CLI
+mise run cmd "/cmd"    # Send single command
+mise run cmd-stats     # Watch performance stats
+mise run topics-init   # Initialize ntfy topics
+
+# Environment
+mise run install       # Install dependencies
+mise run sync          # Sync dependencies
+mise run sync-all      # Sync with all extras
+mise run clean         # Clean cache files
+mise run clobber       # Aggressive cleanup (git clean -fdx + caches)
 ```
 
 ## Git Hooks
@@ -108,6 +132,59 @@ The project uses pytest with strict marker enforcement. Test configuration is in
 - **eventbus.py** provides thread-safe event publishing for decoupled communication
 - **controller.py** coordinates ntfy/mic monitoring
 - The render pipeline: fetch → render → effects → scroll → terminal output
+- **display.py** provides swappable display backends (TerminalDisplay, NullDisplay)
+
+## Operating Modes
+
+Mainline can run in two modes:
+
+### 1. Standalone Mode (Original)
+Run directly as a terminal application with interactive pickers:
+```bash
+mise run run              # news stream
+mise run run-poetry       # poetry mode
+mise run run-firehose     # dense headline mode
+```
+This runs the full interactive experience with font picker and effects picker at startup.
+
+### 2. Daemon + Command Mode (Recommended for Long-Running)
+
+The recommended approach for persistent displays:
+
+```bash
+# Start the daemon (headless rendering)
+mise run daemon
+
+# Send commands via ntfy
+mise run cmd "/effects list"
+mise run cmd "/effects noise off"
+mise run cmd "/effects stats"
+
+# Watch mode (continuous stats polling)
+mise run cmd-stats
+
+# Stop the daemon
+mise run daemon-stop
+```
+
+#### How It Works
+
+- **Daemon**: Runs `mainline.py` in the background, renders to terminal
+- **C&C Topics**: Uses separate ntfy topics (like UART serial):
+  - `klubhaus_terminal_mainline_cc_cmd` - commands TO mainline
+  - `klubhaus_terminal_mainline_cc_resp` - responses FROM mainline
+- **Topics are auto-warmed** on first daemon start
+
+#### Available Commands
+
+```
+/effects list                    - List all effects and status
+/effects <name> on             - Enable an effect
+/effects <name> off            - Disable an effect
+/effects <name> intensity 0.5  - Set effect intensity (0.0-1.0)
+/effects reorder noise,fade,glitch,firehose - Reorder pipeline
+/effects stats                  - Show performance statistics
+```
 
 ## Effects Plugin System
 
@@ -143,15 +220,20 @@ class MyEffect:
 
 ### NTFY Commands
 
-Send messages to the ntfy topic to control effects:
+Send commands via `cmdline.py` or directly to the C&C topic:
 
+```bash
+# Using cmdline tool (recommended)
+mise run cmd "/effects list"
+mise run cmd "/effects noise on"
+mise run cmd "/effects noise intensity 0.5"
+mise run cmd "/effects reorder noise,glitch,fade,firehose"
+
+# Or directly via curl
+curl -d "/effects list" https://ntfy.sh/klubhaus_terminal_mainline_cc_cmd
 ```
-/effects list
-/effects noise on
-/effects noise off
-/effects noise intensity 0.5
-/effects reorder noise,glitch,fade,firehose
-```
+
+The cmdline tool polls the response topic for the daemon's reply.
 
 ## Conventional Commits