intellij-plugin: address automated review feedback (#474)

* Initial plan

* Implement all review feedback: paren tokens, decorator filtering, key patterns, .idea gitignore

Co-authored-by: philmillman <3722211+philmillman@users.noreply.github.com>
Agent-Logs-Url: https://github.com/dmno-dev/varlock/sessions/45f827c0-165e-457c-83dc-538993ffa1bd

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: philmillman <3722211+philmillman@users.noreply.github.com>

Author: Copilot

.gitignore

@@ -17,3 +17,6 @@ framework-tests/.packed
 framework-tests/.test-projects
 .magent
 eslint-output.txt
+
+.idea/
+*.iml

.idea/.gitignore

@@ -71,7 +71,7 @@ Inspired by the [VS Code / Open VSX extension](../../vscode-plugin):
 
 ### Troubleshooting
 
-**Build fails with "What went wrong: 25"** — You're using Java 25, which Gradle 8.x doesn't support. Use Java 17:
+**Build fails with "What went wrong: 25"** — You're using Java 25, which isn't supported by the Gradle/toolchain used for this plugin. Use Java 17:
 
 ```bash
 # Homebrew (openjdk@17)

.idea/codeStyles/Project.xml

@@ -26,23 +26,26 @@ class EnvSpecCompletionContributor : CompletionContributor() {
     }
 
     companion object {
-        private val ENV_KEY_PATTERN = Pattern.compile("^\\s*([A-Za-z_][A-Za-z0-9_]*)\\s*=")
+        private val ENV_KEY_PATTERN = Pattern.compile("^\\s*(?:export\\s+)?([A-Za-z_][A-Za-z0-9_.-]*)\\s*=")
         private val KOTLIN_ESCAPED_DOLLAR_RE = Regex("\\$\\{'\\$'\\}")
         private val CHOICE_SNIPPET_RE = Regex("""\$\{\d+\|([^}]*)\|\}""")
         private val DEFAULT_SNIPPET_RE = Regex("""\$\{\d+:([^}]*)\}""")
         private val TABSTOP_SNIPPET_RE = Regex("""\$\{\d+\}""")
         private val SIMPLE_TABSTOP_SNIPPET_RE = Regex("""\$\d+""")
     }
 
+    private fun getDecoratorCommentPrefix(linePrefix: String): String? {
+        return EnvSpecDiagnosticsCore.getDecoratorCommentText(linePrefix)
+    }
+
     private fun doAddCompletions(params: CompletionParameters, result: CompletionResultSet) {
         val file = params.originalFile as? EnvSpecFile ?: return
         val document = params.editor.document
         val offset = params.offset
         val line = document.getLineNumber(offset)
         val lineStart = document.getLineStartOffset(line)
         val linePrefix = document.getText(com.intellij.openapi.util.TextRange(lineStart, offset))
-        val commentStart = linePrefix.indexOf('#')
-        val commentPrefix = if (commentStart >= 0) linePrefix.substring(commentStart + 1) else ""
+        val commentPrefix = getDecoratorCommentPrefix(linePrefix)
 
         val lineDocument = object : LineDocument {
             override val lineCount: Int get() = document.lineCount
@@ -63,7 +66,7 @@ class EnvSpecCompletionContributor : CompletionContributor() {
             return
         }
 
-        if (commentStart >= 0) {
+        if (commentPrefix != null) {
             val existingDecoratorNames = EnvSpecCompletionCore.getExistingDecoratorNames(lineDocument, line, commentPrefix)
 
             // Type option completion