Address review feedback: ordering and idempotency guard

1. Move session-color definition into the ALWAYS_APPLIED block
   (next to statusline-update-throttle) for ordering consistency.
2. Tighten idempotency check: match the full injection sentinel
   'standaloneAgentContext:(()=>{let __c=process.env.TWEAKCC_SESSION_COLOR;'
   instead of the broad 'TWEAKCC_SESSION_COLOR' substring to avoid
   false-positive early returns.
3. Rebase onto upstream/main to resolve conflict with channels-mode
   patch (#653).

Author: VitalyOstanin

src/patches/sessionColor.ts

@@ -22,7 +22,11 @@ const INJECTION =
   `})()`;
 
 export const writeSessionColor = (oldFile: string): string | null => {
-  if (oldFile.includes('TWEAKCC_SESSION_COLOR')) {
+  if (
+    oldFile.includes(
+      'standaloneAgentContext:(()=>{let __c=process.env.TWEAKCC_SESSION_COLOR;'
+    )
+  ) {
     return oldFile;
   }