DM pairing + Telegram channel improvements (#17)

* feat: Implement DM pairing for channels

- Introduced a new pairing system to manage direct messages from unknown senders.
- Added `PairingStore` to handle pending requests and allowlist management.
- Implemented CLI commands for listing and approving pairing requests.
- Updated Telegram channel to utilize the new pairing logic, including workspace paths for storing pairing data.
- Enhanced WASM channel integration to support pairing functionality.

This feature enhances security by requiring approval for unknown senders before they can interact with the agent.

* Enhance Telegram channel support with media captioning and DM pairing features

- Added support for media captions in Telegram messages, allowing for richer content handling.
- Updated message processing to utilize either text or caption, improving message flexibility.
- Enhanced DM pairing functionality to include approval and listing capabilities for direct messages.
- Updated feature parity documentation to reflect new capabilities and improvements in Telegram integration.

* Update README and BUILDING_CHANNELS documentation for Telegram channel integration

- Enhanced README with instructions for building and running the Telegram channel, including a note on running `./scripts/build-all.sh` for full releases.
- Added detailed steps in BUILDING_CHANNELS.md for building and deploying the Telegram channel, emphasizing the need to run `./channels-src/telegram/build.sh` before building the main crate to ensure updated WASM is included.
- Updated CLI module to expose a new command for pairing with store functionality.

* Implement build script for Telegram channel WASM and enhance pairing error handling

- Added a new `build.rs` script to automate the compilation of the Telegram channel's WASM binary from source, ensuring reproducible builds and emphasizing supply chain security by preventing committed binaries.
- Updated `BUILDING_CHANNELS.md` to reflect the new build process and the importance of not committing compiled binaries.
- Enhanced error handling in the pairing approval process to include rate limiting for failed attempts, improving security and user feedback.

* Remove Telegram channel WASM binary file as part of the build process cleanup, ensuring no committed binaries are present in the repository.

src/cli/mod.rs

@@ -12,12 +12,14 @@
 mod config;
 mod mcp;
 pub mod memory;
+mod pairing;
 pub mod status;
 mod tool;
 
 pub use config::{ConfigCommand, run_config_command};
 pub use mcp::{McpCommand, run_mcp_command};
 pub use memory::{MemoryCommand, run_memory_command};
+pub use pairing::{PairingCommand, run_pairing_command, run_pairing_command_with_store};
 pub use status::run_status_command;
 pub use tool::{ToolCommand, run_tool_command};
 
@@ -86,6 +88,10 @@ pub enum Command {
     #[command(subcommand)]
     Memory(MemoryCommand),
 
+    /// DM pairing (approve inbound requests from unknown senders)
+    #[command(subcommand)]
+    Pairing(PairingCommand),
+
     /// Show system health and diagnostics
     Status,