chore: remove stale LPB_VERSION from lpb.conf.env

LPB_VERSION=0.2.0-lpb was hardcoded in the initial commit and never
updated while VERSION evolved to 0.0.23-lpb-dev. It had no runtime
consumer and its comment about a startup banner was incorrect.

The only real path is build.py → Dockerfile → container (source of
truth). Clean up the stale lpb.conf.env default, the dead lpb.py
env-var pass-through, and the orphaned LOCALPIB_VERSION export.

Author: localpibox

lpb.conf.env

@@ -61,9 +61,7 @@ LPB_AGENT_BROWSER_IDLE_TIMEOUT_MS=300000
 # ─── Misc ───────────────────────────────────────────────────────────────
 # Persist gh CLI auth to ~/.config/gh inside container
 LPB_PERSIST_GH_CONFIG=true
-# LocalPibox stack version (shown in startup banner, set via lpb.stack.env)
-LPB_VERSION=0.2.0-lpb
-
+LPB_PERSIST_GH_CONFIG=true
 # ─── Agent Date/Time ──────────────────────────────────────────────────
 # Set by start.sh at runtime (via $(date)) so the agent always knows
 # the current date/time. Available as PI_DATE and PI_TIME environment

scripts/lpb.py

@@ -893,7 +893,7 @@ def cmd_version():
     stack_env = _find_env_file("lpb.stack.env")
     if stack_env and stack_env.is_file():
         cfg_env = _parse_env_file(stack_env)
-        version = cfg_env.get("LPB_PI_REF", cfg_env.get("LPB_VERSION", "unknown"))
+        version = cfg_env.get("LPB_PI_REF", "unknown")
         print(f"LocalPibox stack {version}")
         return
 
@@ -1202,7 +1202,6 @@ def cmd_run():
         # would pollute .devstack-env and break future host runs.
         f"LPB_EXA_API_KEY={os.environ.get('LPB_EXA_API_KEY', os.environ.get('EXA_API_KEY', ''))}",
         f"LPB_MAX_TOKENS_CONTEXT_RATIO={os.environ.get('LPB_MAX_TOKENS_CONTEXT_RATIO', _conf_cfg.get('LPB_MAX_TOKENS_CONTEXT_RATIO', '0.06'))}",
-        f"LPB_VERSION={os.environ.get('LPB_VERSION', _conf_cfg.get('LPB_VERSION', ''))}",
     ]
     for k in ("PI_WORKTREE_ID", "LPB_AGENT_BROWSER_ARGS", "LPB_AGENT_BROWSER_MAX_OUTPUT",
               "LPB_AGENT_BROWSER_CONTENT_BOUNDARIES", "LPB_AGENT_BROWSER_CONFIRM_ACTIONS",