Allow components to support the req component parameter in Typescript (cloudflare#67)

`http-message-sig` package is currently not compliant with the spec - in
particular, it returns `@authority` as a derived component in the
response, when in reality it should be returning `"@authority";req`.

This makes it impossible to write a compliant HTTP message directory,
for instance.

To support this, I've made several changes:

1. I've defined a new type called `ComponentParameters`, which can store
   arbitrary parameters attached to components. This allows us to expose
   `req`, `bs`, `sf`, etc. and even `key`. I've added it as a variant of
   `Component`.

2. I've replaced the handwritten parser with `structured-headers`
   library, which does the parsing for us. I've done my best to
   preserve the error cases we had in the past, but I've removed cases
   that assumed an unknown parameter meant invalid parsing - unknown
   list parameters are fine to keep and do not imply invalid parsing.

3. I've defined a new type called `ResponseRequestPair`, which bundles
   both request and response together, and written a resolver that
   inspects whether or not a component needs the pair, or can make do
   with just the raw message.

Author: AkshatM

.prettierignore

@@ -0,0 +1,2 @@
+examples/signature-agent-card-and-registry/target/*
+examples/signature-agent-card-and-registry/build/*

examples/httpie-web-bot-auth/README.md

@@ -42,8 +42,8 @@ HTTPIE_WBA_KEY="/path/to/jwk.json" http 'http+wba://example.com'
 
 ### Requirements
 
-* [Python 3.13](https://www.python.org/downloads/)
-* [uv](https://docs.astral.sh/uv/getting-started/installation/) - Python package manager
+- [Python 3.13](https://www.python.org/downloads/)
+- [uv](https://docs.astral.sh/uv/getting-started/installation/) - Python package manager
 
 ### Build
 

examples/signature-agent-card-and-registry/README.md

@@ -1,4 +1,4 @@
-# Example Signature Agent Card and Registry on Cloudflare Workers 
+# Example Signature Agent Card and Registry on Cloudflare Workers
 
 This deploys a registry and a signature agent card on the same host: a Cloudflare worker.
 
@@ -8,8 +8,8 @@ Instructions:
 - Navigate to `http://localhost:8787/.well-known/http-message-signatures-directory` to view a generated signature agent card with an example directory.
 - Navigate to `http://localhost:8787` to view a registry containing this host. Note: this will not be generated until after you've visited `/.well-known/http-message-signatures-directory`, since the card will not exist until then.
 
-This configuration allows you to attach multiple routes and generate an SAC for each one, all viewable in the registry. 
+This configuration allows you to attach multiple routes and generate an SAC for each one, all viewable in the registry.
 
 ## Warning
 
-The JSON web keys produced by this worker are *not cryptographically secure*. You should not use any of the private or public keys generated for message signing or verifying outside of this host. This example is only suitable for insecure use.
+The JSON web keys produced by this worker are _not cryptographically secure_. You should not use any of the private or public keys generated for message signing or verifying outside of this host. This example is only suitable for insecure use.