The `cmdInitMapCodebase` / `initMapCodebase` init handlers did not
include `date` or `timestamp` fields in their JSON output, unlike
`init quick` and `init todo` which both provide them.
Because the mapper agents had no reliable date source, they were forced
to guess the date from model training data, producing incorrect
Analysis Date values (e.g. 2025-07-15 instead of the actual date) in
all seven `.planning/codebase/*.md` documents.
Changes:
- Add `date` and `timestamp` to `cmdInitMapCodebase` (init.cjs) and
`initMapCodebase` (init.ts)
- Pass `{date}` into each mapper agent prompt via the workflow
- Update agent definition to use the prompt-provided date instead of
guessing
- Cover sequential_mapping fallback path as well