chore: remove dead code (#648) (#703)

* chore: remove dead code (LlmEvaluator, chunk_by_paragraphs, bundled channel installer, Reasoning::safety)

Delete unused code flagged in #648:
- evaluation/success.rs: delete LlmEvaluator struct/impl, remove #[allow(dead_code)] from RuleBasedEvaluator methods
- workspace/chunker.rs: delete chunk_by_paragraphs() and its tests (zero production callers)
- extensions/manager.rs: delete install_bundled_channel_from_artifacts() (hot-activation never shipped)
- llm/reasoning.rs: remove unused safety field from Reasoning struct; cascade removal through ContextCompactor, HeartbeatRunner, LlmSoftwareBuilder, and all callers

Closes #648

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: move RuleBasedEvaluator into test module to fix dead_code warning

RuleBasedEvaluator has no production callers -- it was only used in
tests of itself. Moving it into #[cfg(test)] eliminates the clippy
dead_code error that broke CI.

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>

src/llm/reasoning.rs

@@ -11,7 +11,6 @@ use crate::llm::{
     ChatMessage, CompletionRequest, LlmProvider, Role, ToolCall, ToolCompletionRequest,
     ToolDefinition,
 };
-use crate::safety::SafetyLayer;
 
 /// Token the agent returns when it has nothing to say (e.g. in group chats).
 /// The dispatcher should check for this and suppress the message.
@@ -343,8 +342,6 @@ pub struct RespondOutput {
 /// Reasoning engine for the agent.
 pub struct Reasoning {
     llm: Arc<dyn LlmProvider>,
-    #[allow(dead_code)] // Will be used for sanitizing tool outputs
-    safety: Arc<SafetyLayer>,
     /// Optional workspace for loading identity/system prompts.
     workspace_system_prompt: Option<String>,
     /// Optional skill context block to inject into system prompt.
@@ -362,10 +359,9 @@ pub struct Reasoning {
 
 impl Reasoning {
     /// Create a new reasoning engine.
-    pub fn new(llm: Arc<dyn LlmProvider>, safety: Arc<SafetyLayer>) -> Self {
+    pub fn new(llm: Arc<dyn LlmProvider>) -> Self {
         Self {
             llm,
-            safety,
             workspace_system_prompt: None,
             skill_context: None,
             channel: None,
@@ -2117,15 +2113,9 @@ That's my plan."#;
     // ---- System prompt building tests (issue #565) ----
 
     fn make_test_reasoning() -> Reasoning {
-        use crate::config::SafetyConfig;
-        use crate::safety::SafetyLayer;
         use crate::testing::StubLlm;
         let llm = Arc::new(StubLlm::new("test"));
-        let safety = Arc::new(SafetyLayer::new(&SafetyConfig {
-            max_output_length: 100_000,
-            injection_check_enabled: false,
-        }));
-        Reasoning::new(llm, safety)
+        Reasoning::new(llm)
     }
 
     #[test]