Need to run examples as part of CI checks

[b5]

specifically, we've missed:

• iroh_node_discovery chat example
• iroh_pkarr_naming_system CLI example

here are the errors that cropped up for historical purposes. Both of these were fixed in #58. We can close this once CI can confirm a break in examples

❯ cargo build --release --examples
   Compiling iroh-pkarr-node-discovery v0.3.0 (/Users/jay/Documents/code/iroh-examples/iroh-pkarr-node-discovery)
error[E0599]: no method named `iroh_pkarr_relay` found for struct `iroh_pkarr_node_discovery::Builder` in the current scope
  --> examples/chat.rs:54:37
   |
54 |         PkarrRelay::Iroh => builder.iroh_pkarr_relay(),
   |                                     ^^^^^^^^^^^^^^^^ help: there is a method with a similar name: `pkarr_relay`

For more information about this error, try `rustc --explain E0599`.
error: could not compile `iroh-pkarr-node-discovery` (example "chat") due to previous error

~/Documents/code/iroh-examples/iroh-pkarr-naming-system main 37s
❯ cargo run --example cli
   Compiling iroh-pkarr-naming-system v0.1.0 (/Users/jay/Documents/code/iroh-examples/iroh-pkarr-naming-system)
error[E0432]: unresolved import `iroh_net::ticket::BlobTicket`
 --> examples/cli.rs:2:5
  |
2 | use iroh_net::ticket::BlobTicket;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `BlobTicket` in `ticket`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `iroh-pkarr-naming-system` (example "cli") due to previous error