feat: wire lens into research prompts (closes R38)

[wikithoughts]

What

Closes backlog item R38 ("lens-axis") per docs/REVIEW_2026-07.md/docs/ROADMAP.md.

lens (an angle-of-attack instruction like skeptic/opportunity/first_principles/practical, injected as the first line of a model's prompt) has worked for chat jobs since council/worker.py's PerspectiveWorker.answer() — but was inert for research jobs: council/researcher.py's ResearchWorker.lens field existed and was threaded through, but nothing ever read it when building the findings-generation prompt.

This wires it in: ResearchWorker._draft() now computes LENSES.get(self.lens, LENSES["neutral"]) (same fallback pattern worker.py already uses) and injects it as the first instruction bullet, alongside the existing role/vantage/citation bullets. Query planning (_plan_queries/_refine_queries) is untouched — lens shapes only the final synthesis, matching worker.py's own scope (it doesn't lens the question either).

docs/GLOSSARY.md's Lens entry gets a one-clause addition noting this now applies uniformly across pw ask and pw research/network research jobs, since that's what the generic phrasing already implied.

Backward compatibility

council/local.py is intentionally untouched. It hardcodes lens="independent analyst" for single-player pw research — not a key in council.worker.LENSES — so LENSES.get(self.lens, LENSES["neutral"]) safely falls through to the neutral instruction for it, exactly as it already does for any other unknown lens string. This is verified by a dedicated regression test rather than "fixed" in local.py.

Testing

New tests/test_researcher_lens.py:

• _draft()'s prompt carries LENSES["skeptic"]'s text when lens="skeptic".
• _draft()'s prompt carries LENSES["neutral"]'s text with the default lens.
• lens="independent analyst" (the exact string council/local.py hardcodes) does not raise and falls back to the neutral instruction text — the regression guarantee for local.py.

Full verification (all green):

• python -m py_compile council/researcher.py tests/test_researcher_lens.py
• ruff check . → All checks passed!
• pytest tests/ -q → 510 passed, 1 skipped (511 collected total, including the 3 new tests; the 1 skip is pre-existing/unrelated)

Touched only council/researcher.py, tests/test_researcher_lens.py (new), docs/GLOSSARY.md — no changes to council/local.py, council/worker.py, or anything else.

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