fix: extract lib/formula-session.sh to eliminate duplicate code blocks

Shared helpers for formula-driven cron agents: lock, memory guard,
formula loading, context building, session startup, crash recovery.

- planner-run.sh uses shared helpers instead of inline code
- gardener-agent.sh delegates crash recovery to formula_phase_callback
- agent-smoke.sh updated for renamed planner script + new lib file

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.woodpecker/agent-smoke.sh

@@ -91,7 +91,7 @@ echo "=== 2/2  Function resolution ==="
 
 # Functions provided by shared lib files (available to all agent scripts via source)
 LIB_FUNS=$(
-  for f in lib/agent-session.sh lib/env.sh lib/ci-helpers.sh lib/load-project.sh lib/file-action-issue.sh; do
+  for f in lib/agent-session.sh lib/env.sh lib/ci-helpers.sh lib/load-project.sh lib/file-action-issue.sh lib/formula-session.sh; do
     if [ -f "$f" ]; then get_fns "$f"; fi
   done | sort -u
 )
@@ -162,7 +162,7 @@ check_script gardener/gardener-poll.sh
 check_script gardener/gardener-run.sh
 check_script review/review-pr.sh
 check_script review/review-poll.sh
-check_script planner/planner-poll.sh
+check_script planner/planner-run.sh
 check_script supervisor/supervisor-poll.sh
 check_script supervisor/update-prompt.sh
 check_script vault/vault-agent.sh