fix(workspace): default hook cwd to workspaceFileDir for file-referenced templates

[christso]

Summary

When a workspace is defined via a file reference (e.g., workspace: .templates/eval-workspace-setup.yaml), hook commands with no explicit cwd now resolve relative to the workspace file's directory instead of the eval file's directory.

This makes file-referenced templates self-contained — the same template produces identical behavior regardless of which eval file references it.

• Added workspaceFileDir to WorkspaceConfig — set when workspace is resolved from a file reference
• Added workspaceFileDir to ScriptExecutionContext — passed through from workspace config
• Changed cwd fallback chain: config.cwd → context.workspaceFileDir → context.evalDir
• Preserved workspaceFileDir in mergeWorkspaceConfigs

Closes #1080

Test plan

• New unit tests verify workspaceFileDir takes priority over evalDir when no explicit cwd is set
• New unit tests verify explicit cwd still overrides workspaceFileDir
• New unit tests verify workspaceFileDir is set for file references and undefined for inline configs
• Existing tests still pass (1615 core tests, 67 eval tests)
• All pre-push hooks pass (build, typecheck, lint, test, validate)
• Manual red/green UAT with nested eval file referencing a shared template

🤖 Generated with Claude Code

[cloudflare-workers-and-pages]

Deploying agentv with    Cloudflare Pages

Latest commit:	6926e8b
Status:	✅  Deploy successful!
Preview URL:	https://3d4c5dab.agentv.pages.dev
Branch Preview URL:	https://fix-1080-hook-cwd-workspace.agentv.pages.dev

View logs

[christso]

Red/Green UAT

Setup

Directory structure:

/tmp/uat-1080/
  scripts/check.mjs                          # Hook script
  evals/
    templates/
      workspace.yaml                         # command: ["node", "../../scripts/check.mjs"]
    group-a/
      root-eval.eval.yaml                    # workspace: ../templates/workspace.yaml
      subdir/
        nested-eval.eval.yaml                # workspace: ../../templates/workspace.yaml

The template uses ../../scripts/check.mjs — a relative path that resolves correctly from evals/templates/ (the template's directory) but not from evals/group-a/subdir/ (the nested eval's directory).

Red (main) — nested eval fails

$ bun apps/cli/src/cli.ts eval nested-eval.eval.yaml --dry-run

[ERROR] ⚠ Eval file failed: nested-eval.eval.yaml — before_all script failed:
  Script failed: error: Module not found '/tmp/uat-1080/evals/scripts/check.mjs'

The hook's cwd defaulted to evalDir (evals/group-a/subdir/), so ../../scripts/check.mjs resolved to /tmp/uat-1080/evals/scripts/check.mjs instead of /tmp/uat-1080/scripts/check.mjs.

Root eval on main: ✅ (cwd happened to be at the right depth — evals/group-a/)

Green (fix branch) — both evals pass

$ bun apps/cli/src/cli.ts eval root-eval.eval.yaml --dry-run    → EXIT CODE: 0 ✅
$ bun apps/cli/src/cli.ts eval nested-eval.eval.yaml --dry-run  → EXIT CODE: 0 ✅

Both evals now use workspaceFileDir (evals/templates/) as default cwd, so ../../scripts/check.mjs resolves to /tmp/uat-1080/scripts/check.mjs consistently regardless of eval file depth.

(Scores are 0% as expected with --dry-run — the key signal is no execution errors on the hook.)