refactor(dataflow): give declared-type reading its own home

[RaghavChamadiya]

BaseDefUseDialect (27 methods) read declared types over its own kind sets (type_holder_kinds / type_wrapper_kinds), a separate responsibility that kept its LCOM4 at 2 (low_cohesion, high).

That reading now lives in a small DeclaredTypes dataclass in base.py, exposed on each dialect as declared_types. Per-language overrides keep working: C++ (* / & / const) and TypeScript (optional parameter | undefined) subclass it in their own modules. The one outside caller, extract_method _declared_types, calls dialect.declared_types.of(node).

• BaseDefUseDialect: LCOM4 2 -> 1 (also 1 with fix(health): stop counting field-less cohesion groups in explicit-receiver classes #3552 applied); no sibling dialect regresses, new classes are LCOM4 1.
• Behaviour unchanged, no analyzer version bump.
• Tests: tests/unit/health dataflow + extract_method (603 passed).

[repowise-bot]

Reviewed the whole diff: nothing to fix.

✅ Health of changed files: 5.1 (unchanged)
_{56% of the added lines moved unchanged from other files, so this mostly reflects the new file layout.}

Check	Result
Coverage	Waiting for this PR's CI to upload a report (last report from this repo just now)
Tests	8 of 8 changed code files reached by a test · which tests
Security	No new findings on changed lines
Doc drift	No drift in docs this PR edits

---

📊 See the full report for this PR
_{Blast radius, every caller of the contracts it changes, and health before and after. No sign-in.
Reviewed with AI · Plain markdown for agents}

_{Settings and updates}

_{Updated 2026-10-11 19:16 UTC
Silence one PR with [skip repowise] in the title · Bot settings
⭐ Star Repowise · 📥 Install on another repo}