feat(context): tambah context::dedup untuk hasil tool yang berulang

Panggilan tool read-only (read, grep, glob, dst) dengan argumen persis
sama menyisakan satu salinan penuh saja di context; entri lama diganti
placeholder tapi tool-call-nya sendiri tetap terlihat di riwayat. Tool
bersifat mutasi (write/edit/bash/dll) tidak pernah disentuh.

Jadikan tool_scope::READ_TOOLS pub supaya jadi satu-satunya sumber
klasifikasi read-only, dipakai ulang bukan didaftar dua kali.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/subagent/division.rs

@@ -18,7 +18,10 @@ pub mod tool_scope {
     /// Write-tier plus delete, git, and the remaining LSP actions.
     pub const FULL: &str = "full";
 
-    const READ_TOOLS: &[&str] = &[
+    /// The read-only tool set — reused by `context::dedup` as the
+    /// authoritative "safe to deduplicate" classification, so there's a
+    /// single list of read-only tool names in the codebase instead of two.
+    pub const READ_TOOLS: &[&str] = &[
         "read", "grep", "glob", "search", "seqthink", "recall",
         "lsp_connect", "lsp_diagnostics", "lsp_hover", "lsp_definition",
         "lsp_references", "read_findings",