perf: Speed up conflict resolution agents by trimming prompt bloat

Replace SESSION_STARTUP (full test suite run) and CONTEXT_MANAGEMENT
(progress file refs) with a minimal startup block (pwd, git status,
CLAUDE.md). Add skipPromptExtras option to SpawnAgentOptions to skip
inter-agent communication and preview deployment instructions. Conflict
agents now go straight to the resolution protocol — one post-resolution
test run instead of two.

apps/server/trpc/routers/initiative.ts

@@ -488,6 +488,7 @@ export function initiativeProcedures(publicProcedure: ProcedureBuilder) {
           initiativeId: input.initiativeId,
           baseBranch: initiative.branch,
           branchName: tempBranch,
+          skipPromptExtras: true,
         });
       }),
   };