fix: align Workdir session cwd and model environment

Project alias, cwd, scope and command ceilings from actual sessions. Bind initial attachment cwd once in the shared broker/router while keeping root-relative delegation and detach generations. Preserve caller coordinates across reads, searches, checked checkout and commands; keep provider authorization and symlink boundaries.

Connect real SubWorkers, all filesystem Tools, scoped aliases, HTTP providers and limited Host grants in permanent regressions. Validated related normal suites (workdir http-client, tools, worker, worker-runtime, server-api typescript, fs-operation), workspace-server normal suite (1272 passed, 3 existing ignores), root check, product binary builds, rustdoc/doctests, generated contract checks, format and state-contract names. Test roots are checkout-local; Git parent discovery requires GIT_CEILING_DIRECTORIES at TMPDIR, confirmed against exact b860 baseline.

crates/worker/tests/system_prompt_template_test.rs

@@ -187,7 +187,8 @@ async fn materialise_on_first_turn_populates_worker() {
         .expect("system prompt materialised")
         .to_string();
     assert!(rendered.contains("date="));
-    assert!(rendered.contains(&pwd.display().to_string()));
+    assert!(rendered.contains("## Workdir execution environment"));
+    assert!(!rendered.contains(&pwd.display().to_string()));
     assert!(rendered.starts_with("date="));
 }
 
@@ -206,7 +207,8 @@ async fn session_start_state_captures_rendered_prompt() {
         LogEntry::AnnotatedSegmentStart { system_prompt, .. } => {
             let sp = system_prompt.as_deref().expect("system prompt set");
             assert!(sp.starts_with("hello"));
-            assert!(sp.contains(&pwd.display().to_string()));
+            assert!(sp.contains("## Workdir execution environment"));
+            assert!(!sp.contains(&pwd.display().to_string()));
         }
         other => panic!("expected AnnotatedSegmentStart as first entry, got {other:?}"),
     }