#20526: fix(session-memory): search state-dir sessions path when workspace differs

## Problem When `workspaceDir` ≠ `stateDir` (common when workspace is a custom directory like `~/clawd` while state lives in `~/.openclaw`), the session-memory hook only searched `workspaceDir/sessions` for previous transcripts after `/new` or `/reset`. The actual JSONL session files live in `~/.openclaw/agents/<id>/sessions/`, so the hook never found them — resulting in empty memory files with only 5 lines of metadata. This is the root cause that recent fixes (19ae7a4, d6acd71, 3fff266) were circling around. Those addressed `.reset.` file rotation but missed the fundamental path mismatch. ## Fix Add `stateDir/agents/<agentId>/sessions` to the search paths in `saveSessionToMemory`. 3 lines, uses the already-imported `resolveStateDir`. ## Testing - Tested locally: `/new` now generates complete memory files with conversation summaries - `pnpm build` passes - AI-assisted (Claude), fully tested locally <!-- greptile_comment --> <h3>Greptile Summary</h3> Fixes the root cause of incomplete session memory files by adding the actual state directory sessions path (`~/.openclaw/agents/<agentId>/sessions`) to the search locations when `workspaceDir` differs from `stateDir`. - The session-memory hook now searches three locations: the current session file directory, `workspaceDir/sessions`, and `stateDir/agents/<agentId>/sessions` - Previously only searched `workspaceDir/sessions`, which caused the hook to miss actual session transcripts living in `~/.openclaw/agents/<id>/sessions/` - This resulted in empty memory files containing only 5 lines of metadata after `/new` or `/reset` commands - The fix is minimal (3 lines), uses the already-imported `resolveStateDir` function, and follows the same pattern as other parts of the codebase that need to access per-agent session files <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The fix is surgical, well-tested locally, and addresses a clear path mismatch bug. The implementation uses existing utility functions, follows established patterns throughout the codebase (as seen in 20+ other files that use the same `stateDir/agents/<agentId>/sessions` path pattern), and is covered by the existing test suite that already verifies session file recovery logic - No files require special attention _{Last reviewed commit: 03bd9a1} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->