refactor(campaigns): extract CPM_BANNER_CAMPAIGN to _campaigns_cpm_banner.py (#613)

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Summary

Step 2 of the incremental campaigns.py split (epic #602). Stacked on PR #612 (Step 0 — shared helpers). Extracts the CPM_BANNER_CAMPAIGN add/update subtype-block composition into a new sibling module.

Smallest campaign type → validates the per-type extraction mechanics before the larger types.

What moved

The former inline elif campaign_type_norm == "CPM_BANNER_CAMPAIGN": branches in add (~34 lines) and update (~45 lines) → new module direct_cli/commands/_campaigns_cpm_banner.py:

• build_add_block(p, campaign_data, parsed_settings, counter_ids_obj, frequency_cap_obj)
• build_update_block(p, sub_block)

Both commands now snapshot their CLI parameters once (p = dict(locals())) and delegate; the per-type builder pulls only the CPM-relevant flags from p.

CLI surface

No breaking changes. Every flag, every --dry-run payload byte-for-byte identical. Pure internal relocation — no legacy aliases, strict WSDL parity preserved.

Tests run

• pytest tests/test_dry_run.py -k cpm: 28 passed
• pytest (full offline tier): 2507 passed, 8 skipped (identical to baseline)
• pytest tests/test_wsdl_parity_gate.py tests/test_api_coverage.py: 263 passed, 6 skipped (green)
• black + flake8 — my files clean (only pre-existing E501 long-line warnings)

Risks / follow-ups

• COMMAND_WSDL_MAP not touched.
• This PR is stacked on refactor(campaigns): extract shared helpers to _campaigns_base.py (#602, step 1) #612 — rebase/retarget to main after refactor(campaigns): extract shared helpers to _campaigns_base.py (#602, step 1) #612 merges.
• Per-type extraction pattern established here will be reused for the remaining types (refactor(campaigns): extract MOBILE_APP_CAMPAIGN to _mobile_app.py (#602, step 2) #614 mobile_app → refactor(campaigns): extract SMART_CAMPAIGN to _smart.py (#602, step 3) #615 smart → refactor(campaigns): extract DYNAMIC_TEXT_CAMPAIGN to _dynamic.py (#602, step 4) #616/refactor(campaigns): extract UNIFIED_CAMPAIGN to _unified.py (#602, step 5) #617/refactor(campaigns): extract TEXT_CAMPAIGN to _text.py (#602, step 6) #618 text family).

Closes #613. Part of #602.

🤖 Generated with Claude Code

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📋 Review summary — all cycles (local review)

Reviewed locally with /review (Claude) + Codex companion (gpt-5.6-sol, xhigh). No GitHub bots pinged. Both reviewers approved across both cycles.

Cycle	Reviewer	Finding	Verdict	Resolution
1	claude	# noqa: F401 on genuinely-useded Dict import is misleading	SKIP→fixed	Removed in 5384996 (cycle-2 cleanup)
1	claude	p = dict(locals()) captures Click ctx (cycles)	SKIP	Left as-is — negligible; noted for future serializable-p needs
1	codex	— (behaviorally equivalent, 19 tests pass)	approve	—
2	claude	cleanup is correct, no behavioral change	approve	—
2	codex	Ship: no critical issue, 13 tests pass	approve	—

Totals: 0 FIX, 1 SKIP (1 later applied as cleanup), 0 UNVERIFIED. CLI surface byte-for-byte identical.

Local review is review-only on merge — merge is yours to trigger (PR is stacked on #612, so rebase to main after #612 lands first).