refactor(pipeline): rename dream → think/thinking across codebase
Clean-break rename of the background-analysis pipeline. No aliases, no
compat shims: `sol dream` is gone, `think.dream` is unimportable.
- Subcommand `sol dream` → `sol think`
- Module `think/dream.py` → `think/thinking.py` (asymmetric by design:
verb is `think`, module noun is `thinking`, class is
`ThinkingJSONLWriter`)
- Callosum tract `"dream"` → `"think"`
- Health sidecar filenames drop `_dream`: `{ref}_{mode}.jsonl` and
`{ref}_{mode}.log` (no `_think` replacement)
- `apps/entities/events.py` dead `dream.generators_completed` listener
removed (handler subscribed to an event the pipeline never emitted)
Pre-rename journal logs under `journal/**/*_dream.{log,jsonl}` are left
untouched as historical artifacts (accepted history blackout).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>