Fix/rescue 227 regressions (#232)

* fix: restore regressions introduced by #227

#227 deleted build.rs (reverting #224's version-from-tag feature),
removed DOM cycle guards in append_child/insert_before that prevent
infinite loops on self-append/self-insert, dropped the CharacterData
textContent fast-path, removed PI/Doctype Rust ops, and cut the
env_allows_private_network() check from validate_fetch_url.

Restored:
- crates/obscura-cli/build.rs (version from tag/env)
- OBSCURA_BUILD_VERSION in version string and banner
- allow_private_network env var propagation in main.rs
- append_child/insert_before self-cycle guards in tree.rs
- textContent CharacterData fast-path in tree.rs
- create_processing_instruction, create_doctype, pi_target,
  doctype_name, doctype_public_id ops in ops.rs
- ProcessingInstruction branch in set_text_content op
- env_allows_private_network() check in validate_fetch_url

* fix(js): Europe/Berlin timezone, plugins iterator recursion

Two bugs in the stealth bootstrap code from #227:
- 'Europe/Germany' is not a valid IANA timezone; Intl.DateTimeFormat
  silently fell back to UTC. Changed to 'Europe/Berlin'.
- plugins[Symbol.iterator] called this[Symbol.iterator]() recursively,
  blowing the stack on Array.from(navigator.plugins). Fixed to bind
  Array.prototype[Symbol.iterator] directly to the array.

crates/obscura-js/src/ops.rs

@@ -259,6 +259,7 @@ fn op_dom(state: &OpState, #[string] cmd: String, #[string] arg1: String, #[stri
                 match &mut n.data {
                     NodeData::Text { contents } => { *contents = arg2.clone(); }
                     NodeData::Comment { contents } => { *contents = arg2.clone(); }
+                    NodeData::ProcessingInstruction { data, .. } => { *data = arg2.clone(); }
                     _ => {}
                 }
             });
@@ -279,6 +280,47 @@ fn op_dom(state: &OpState, #[string] cmd: String, #[string] arg1: String, #[stri
         "create_comment_node" => {
             dom.new_node(NodeData::Comment { contents: arg1.clone() }).index().to_string()
         }
+        "create_processing_instruction" => {
+            // arg1 = target, arg2 = data
+            dom.new_node(NodeData::ProcessingInstruction {
+                target: arg1.clone(),
+                data: arg2.clone(),
+            }).index().to_string()
+        }
+        "create_doctype" => {
+            // arg1 = name, arg2 = public_id. system_id stored only in the
+            // JS wrapper since neither current WPT test reads it back from
+            // the underlying tree.
+            dom.new_node(NodeData::Doctype {
+                name: arg1.clone(),
+                public_id: arg2.clone(),
+                system_id: String::new(),
+            }).index().to_string()
+        }
+        "pi_target" => {
+            let nid = arg1.parse::<u32>().unwrap_or(0);
+            let val = dom.get_node(NodeId::new(nid)).and_then(|n| match &n.data {
+                NodeData::ProcessingInstruction { target, .. } => Some(target.clone()),
+                _ => None,
+            }).unwrap_or_default();
+            serde_json::to_string(&val).unwrap_or("\"\"".into())
+        }
+        "doctype_name" => {
+            let nid = arg1.parse::<u32>().unwrap_or(0);
+            let val = dom.get_node(NodeId::new(nid)).and_then(|n| match &n.data {
+                NodeData::Doctype { name, .. } => Some(name.clone()),
+                _ => None,
+            }).unwrap_or_default();
+            serde_json::to_string(&val).unwrap_or("\"\"".into())
+        }
+        "doctype_public_id" => {
+            let nid = arg1.parse::<u32>().unwrap_or(0);
+            let val = dom.get_node(NodeId::new(nid)).and_then(|n| match &n.data {
+                NodeData::Doctype { public_id, .. } => Some(public_id.clone()),
+                _ => None,
+            }).unwrap_or_default();
+            serde_json::to_string(&val).unwrap_or("\"\"".into())
+        }
         "element_children" => {
             let nid = arg1.parse::<u32>().unwrap_or(0);
             let ids: Vec<i32> = dom.children(NodeId::new(nid)).iter()
@@ -726,7 +768,7 @@ fn validate_fetch_url(url: &url::Url) -> Result<(), String> {
         ));
     }
 
-    if scheme == "file" {
+    if scheme == "file" || obscura_net::env_allows_private_network() {
         return Ok(());
     }