Remove test_plan gate from the codebase

The test_plan field was a gate from the old interactive web UI workflow
where a human would approve a test plan before the LLM could write code.
With autonomous coder agents, this gate is dead weight — coders sometimes
obey the README's "wait for approval" instruction and produce no code.

Removes: TestPlanStatus enum, ensure_test_plan_approved checks in fs/shell,
set_test_plan MCP tool + handler, test_plan from story/bug front matter
creation, test_plan validation in validate_story_dirs, and all related tests.
Updates README to remove Step 2 (Test Planning) and renumber steps.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/io/story_metadata.rs

@@ -1,16 +1,8 @@
 use serde::Deserialize;
 
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub enum TestPlanStatus {
-    Approved,
-    WaitingForApproval,
-    Unknown(String),
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct StoryMetadata {
     pub name: Option<String>,
-    pub test_plan: Option<TestPlanStatus>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -31,7 +23,6 @@ impl std::fmt::Display for StoryMetaError {
 #[derive(Debug, Deserialize)]
 struct FrontMatter {
     name: Option<String>,
-    test_plan: Option<String>,
 }
 
 pub fn parse_front_matter(contents: &str) -> Result<StoryMetadata, StoryMetaError> {
@@ -60,11 +51,8 @@ pub fn parse_front_matter(contents: &str) -> Result<StoryMetadata, StoryMetaErro
 }
 
 fn build_metadata(front: FrontMatter) -> StoryMetadata {
-    let test_plan = front.test_plan.as_deref().map(parse_test_plan_status);
-
     StoryMetadata {
         name: front.name,
-        test_plan,
     }
 }
 
@@ -80,14 +68,6 @@ pub fn parse_unchecked_todos(contents: &str) -> Vec<String> {
         .collect()
 }
 
-fn parse_test_plan_status(value: &str) -> TestPlanStatus {
-    match value {
-        "approved" => TestPlanStatus::Approved,
-        "waiting_for_approval" => TestPlanStatus::WaitingForApproval,
-        other => TestPlanStatus::Unknown(other.to_string()),
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -96,7 +76,6 @@ mod tests {
     fn parses_front_matter_metadata() {
         let input = r#"---
 name: Establish the TDD Workflow and Gates
-test_plan: approved
 workflow: tdd
 ---
 # Story 26
@@ -107,7 +86,6 @@ workflow: tdd
             meta,
             StoryMetadata {
                 name: Some("Establish the TDD Workflow and Gates".to_string()),
-                test_plan: Some(TestPlanStatus::Approved),
             }
         );
     }