feat: make schema hash and version constants opt-in via -schemaHash

The schema hash in the file header comment and the WebRPCSchemaHash constant
change on every schema edit, producing perpetual git merge conflicts in
generated files. The version constants (WebRPCVersion, WebRPCSchemaVersion,
WebRPCSchemaHash) are rarely consumed.

Gate them behind a new -schemaHash target option (default false), flipping the
previous always-on behavior:

- default: header comment carries only the name and version (no hash), and no
  version constants are emitted. The "Code generated by ... DO NOT EDIT." line stays.
- with -schemaHash: restores today's output exactly (hash in the header plus all
  three constants).

Regenerated _examples to reflect the new default.

Author: klaidliadon

_examples/hello-webrpc/webapp/client.gen.js

@@ -1,18 +1,9 @@
-// hello-webrpc v1.0.0 949b00a8db9810c69295f9dd9f02587a65d3c497
+// hello-webrpc v1.0.0
 // --
 // Code generated by webrpc-gen@v0.37.0 with ../../ generator. DO NOT EDIT.
 //
 // webrpc-gen -schema=hello-api.ridl -target=../../ -exports=false -client -out=./webapp/client.gen.js
 
-// WebRPC description and code-gen version
-const WebRPCVersion = "v1"
-
-// Schema version of your RIDL schema
-const WebRPCSchemaVersion = "v1.0.0"
-
-// Schema hash generated from your RIDL schema
-const WebRPCSchemaHash = "949b00a8db9810c69295f9dd9f02587a65d3c497"
-
 //
 // Types
 //

main.go.tmpl

@@ -5,6 +5,7 @@
 {{- set $opts "client" (ternary (in .Opts.client "" "true") true false) -}}
 {{- set $opts "server" (ternary (in .Opts.server "" "true") true false) -}}
 {{- set $opts "exports" (ternary (in .Opts.exports "false") false true) -}}
+{{- set $opts "schemaHash" (ternary (in .Opts.schemaHash "" "true") true false) -}}
 
 {{- /* Print help on -help. */ -}}
 {{- if exists .Opts "help" -}}
@@ -52,12 +53,13 @@
 {{- set $typeMap "string" "string" -}}
 {{- set $typeMap "timestamp" "string" -}}
 
-// {{.SchemaName}} {{.SchemaVersion}} {{.SchemaHash}}
+// {{.SchemaName}} {{.SchemaVersion}}{{if $opts.schemaHash}} {{.SchemaHash}}{{end}}
 // --
 // Code generated by webrpc-gen@{{.WebrpcGenVersion}} with {{.WebrpcTarget}} generator. DO NOT EDIT.
 //
 // {{.WebrpcGenCommand}}
 
+{{- if $opts.schemaHash }}
 // WebRPC description and code-gen version
 {{if $opts.exports}}export {{end}}const WebRPCVersion = "{{.WebrpcVersion}}"
 
@@ -66,6 +68,7 @@
 
 // Schema hash generated from your RIDL schema
 {{if $opts.exports}}export {{end}}const WebRPCSchemaHash = "{{.SchemaHash}}"
+{{- end }}
 
 {{template "types" dict "Services" .Services "Types" .Types "Opts" $opts}}
 {{- if $opts.client}}