tools: each module exports only tool() or tools(), nothing else

Every tool module now has a clean interface:
- read, write, edit, grep, glob, bash, vision: pub fn tool() -> Tool
- web: pub fn tools() -> [Tool; 2]
- memory: pub fn memory_tools() -> Vec<Tool>
- channels: pub fn tools() -> Vec<Tool>
- control: pub fn tools() -> Vec<Tool>

Definition and handler functions are private to each module.
mod.rs::tools() just chains the module exports.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/tools/web.rs

@@ -6,6 +6,13 @@ use serde_json::json;
 
 use super::ToolDef;
 
+pub fn tools() -> [super::Tool; 2] {
+    [
+        super::Tool { def: fetch_definition(), handler: |_a, v| Box::pin(async move { web_fetch(&v).await }) },
+        super::Tool { def: search_definition(), handler: |_a, v| Box::pin(async move { web_search(&v).await }) },
+    ]
+}
+
 // ── Fetch ───────────────────────────────────────────────────────
 
 #[derive(Deserialize)]
@@ -13,7 +20,7 @@ struct FetchArgs {
     url: String,
 }
 
-pub fn fetch_definition() -> ToolDef {
+fn fetch_definition() -> ToolDef {
     ToolDef::new(
         "web_fetch",
         "Fetch content from a URL and return it as text. \
@@ -31,7 +38,7 @@ pub fn fetch_definition() -> ToolDef {
     )
 }
 
-pub async fn web_fetch(args: &serde_json::Value) -> Result<String> {
+async fn web_fetch(args: &serde_json::Value) -> Result<String> {
     let a: FetchArgs = serde_json::from_value(args.clone())
         .context("invalid web_fetch arguments")?;
 
@@ -64,7 +71,7 @@ struct SearchArgs {
 
 fn default_num_results() -> usize { 5 }
 
-pub fn search_definition() -> ToolDef {
+fn search_definition() -> ToolDef {
     ToolDef::new(
         "web_search",
         "Search the web and return results. Use for finding \
@@ -86,7 +93,7 @@ pub fn search_definition() -> ToolDef {
     )
 }
 
-pub async fn web_search(args: &serde_json::Value) -> Result<String> {
+async fn web_search(args: &serde_json::Value) -> Result<String> {
     let a: SearchArgs = serde_json::from_value(args.clone())
         .context("invalid web_search arguments")?;