add http/httphi (#171)

* add http/httphi

* begin adding httphi tests

* claude found neat bugs

* add low level Handle function and more tests

* more tests, run go generate

* add Hijacker-like functionality

* improve locking and acquisition of Exchanges in reconfiguring

* several bugfixes, add internal.IntLen, round up http-linux example with new router API

* small nit

* add benchmarks

* add query handling

* remove ForEach pattern, allocates in TinyGo

* massive documentation push and code reordering in files

* Router.Handle returns error after being torn down

* run go fix

* rework Mux interface to receive a string request path

* add MethodFrom

* minor doc nit

* fail on incomplete staging

* add raw buffer access

* add streaming API distinct from Exchange

* begin adding multipart form logic

* finish rounding up multipart form parsing

* remove status type

* first Multipart approach

* begin adding readMultiPart

* add Exchange.ReadMultiparts reimagining of clanker slop

* ai insists with backoffs

* simplify clanker slop

* apply go fix

* add a pattern argument to Mux

* explicit header key/value alloc and add ExchangeConfig

* fix tests after excplicit header alloc change

* fix examples

* run go fix

* expose rawsock as experimental package (will use for external benchmarks)

* remove backoff from form parsing

* @MDr164 suggestions get potential fixes

* apply go fix

* add examples

* add README.md

* fix rawsock tinygo implementation

* apply @MDr164 various fixes

* update documentation on ContentLength methods and fix bug in Form reset on empty body

* fix tests

* add fuzz tests

* run go fix

* io.ErrNoProgress on parsing form spin

* run go fix

* remove backoff assumption from Router

* httphi.Handle rejects unsupported protocols

* go format router.go

* add kvbuffer

* rewrite Cookie with KVBuffer

* mid refactor of KVBuffer into Header

* work on KVBuffer exhausted semantics

* add Go's ServeMux Request.PathValue access semantics to Exchange, Mux and MuxSlice

* add PathValue example

* document all the things; improve req Query semantics; add Form.EnableBufferGrowth

* unexport kvBuffer

* add Exchange.PathValueAppend

* use stdlib in example instead of rawsock

* remove rawsock from http example

* add darwin arch rawsock

* fix example

* rename Router.TeardownGoroutines to Shutdown matching http.Server.Shutdown

* rename types and identifiers

* @MDr164 Content-Type and Transfer-Encoding bug catches

stringers.go

@@ -212,16 +212,17 @@ func _() {
 	_ = x[ErrAlreadyRegistered-17]
 	_ = x[ErrTruncatedFrame-18]
 	_ = x[ErrMissingHALConfig-19]
+	_ = x[ErrBadState-20]
 }
 
 const (
 	_errGeneric_name_0 = "lneto-bug(use build tag \"debugheaplog\")packet droppedincorrect checksumzero source(port/addr)zero destination(port/addr)short bufferbuffer fullinvalid addressunsupportedmismatchmismatched lengthinvalid configuration"
-	_errGeneric_name_1 = "invalid fieldinvalid length fieldresource exhaustedprotocol already registeredtruncated framemissing HAL configuration"
+	_errGeneric_name_1 = "invalid fieldinvalid length fieldresource exhaustedprotocol already registeredtruncated framemissing HAL configurationoperation invalid in current state"
 )
 
 var (
 	_errGeneric_index_0 = [...]uint8{0, 39, 53, 71, 93, 120, 132, 143, 158, 169, 177, 194, 215}
-	_errGeneric_index_1 = [...]uint8{0, 13, 33, 51, 78, 93, 118}
+	_errGeneric_index_1 = [...]uint8{0, 13, 33, 51, 78, 93, 118, 152}
 )
 
 func (i errGeneric) String() string {
@@ -229,7 +230,7 @@ func (i errGeneric) String() string {
 	case 1 <= i && i <= 12:
 		i -= 1
 		return _errGeneric_name_0[_errGeneric_index_0[i]:_errGeneric_index_0[i+1]]
-	case 14 <= i && i <= 19:
+	case 14 <= i && i <= 20:
 		i -= 14
 		return _errGeneric_name_1[_errGeneric_index_1[i]:_errGeneric_index_1[i+1]]
 	default: