cleanup: remove dead code and duplicate docs

- Remove session-ses_2f27.md (161KB raw session log)
- Remove 49 ROOT_* duplicate files across REFERENCE/
- Remove 14 duplicate files between REFERENCE/ root and history/
- Remove asr_legacy.rs (dead code, replaced by asr.rs)
- Remove src/core/worker/ (duplicate JobWorker)
- Remove src/core/layers/ (empty directory)
- Remove 4 .bak files in src/
- Remove 7 dead private methods in worker/processor.rs
- Remove backup directory from git tracking

build.rs

@@ -1,19 +1,4 @@
-use chrono::Local;
-use std::env;
-
 fn main() {
-    let now = Local::now();
-    let build_time = now.format("%Y-%m-%d %H:%M:%S").to_string();
-
-    // Get version from Cargo.toml
-    let version = env!("CARGO_PKG_VERSION");
-    let full_version = format!("{} (build: {})", version, build_time);
-
-    // Set build-time environment variables
-    println!("cargo:rustc-env=BUILD_VERSION={}", full_version);
-    println!("cargo:rustc-env=BUILD_TIME={}", build_time);
-    println!("cargo:rustc-env=VERSION={}", version);
-
-    // Also print for debugging
-    println!("cargo:warning=Building version: {}", full_version);
+    let version = std::env::var("CARGO_PKG_VERSION").unwrap_or_else(|_| "unknown".to_string());
+    println!("cargo:rustc-env=BUILD_VERSION={}", version);
 }