feat: track subagent mode globally in all PostHog events

Move subagent tracking from a single event property to the ph() function
so every PostHog event is automatically tagged with subagent: true/false.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mohamedashrraf222

codeflash/optimization/optimizer.py

@@ -486,7 +486,7 @@ def rank_by_dependency_count(
     def run(self) -> None:
         from codeflash.code_utils.checkpoint import CodeflashRunCheckpoint
 
-        ph("cli-optimize-run-start", {"subagent": is_subagent_mode()})
+        ph("cli-optimize-run-start")
         logger.info("Running optimizer.")
         console.rule()
         if not env_utils.ensure_codeflash_api_key():

codeflash/telemetry/posthog_cf.py

@@ -7,6 +7,7 @@
 
 from codeflash.api.cfapi import get_user_id
 from codeflash.cli_cmds.console import logger
+from codeflash.lsp.helpers import is_subagent_mode
 from codeflash.version import __version__
 
 _posthog = None
@@ -36,7 +37,7 @@ def ph(event: str, properties: dict[str, Any] | None = None) -> None:
         return
 
     properties = properties or {}
-    properties.update({"cli_version": __version__})
+    properties.update({"cli_version": __version__, "subagent": is_subagent_mode()})
 
     user_id = get_user_id()