feat(reports): BYOM providers + model profiles

Parent: #145

Scope

Implement decomposition item 7: device-local BYOM provider/model profiles, official OpenAI/Anthropic and custom OpenAI-/Anthropic-compatible HTTPS adapters, retention warnings, browser-direct/CORS handling, model defaults and per-operation overrides.

Dependencies

Requires the Case Facts/disclosure contract from #269/#271. Provider-adapter work may proceed in parallel after those contracts stabilize; final editor integration must conform to #272 provider/provenance interfaces.

Required invariants

• Secrets stay device-local/unsynced and must never enter Dexie-synced Case data, logs, URLs, D1/R2, telemetry, exports, or provenance snapshots.
• Explicit provider/model/endpoint disclosure before transmission; renewed consent for newly disclosed sensitive context.
• Official OpenAI and Anthropic warnings must match the exact #145 researched retention/training wording; custom endpoints carry an explicit unknown-policy warning and no unverified ZDR claim.
• Custom endpoints require HTTPS except explicitly permitted localhost development behavior; failures distinguish CORS/HTTP/provider/validation safely.
• Adapters use the same validated structured response/provenance constraints as app-funded AI.
• TDD and full AGENTS.md gates.

Acceptance

Implement all #145 decomposition-item-7 requirements with secret-leakage tests, storage-boundary tests, adapter contract tests, warning/consent UI tests, and relevant desktop/mobile E2E.

Read decomposition item 7 in #145, the Case Facts/disclosure contracts in #269/#271, the provider/provenance interfaces in #272, and the repository's AGENTS.md gates. Map the device-local secret boundary, provider adapters, consent and warning flows, then add the requested leakage, storage-boundary, adapter, UI, and desktop/mobile E2E tests; done means all stated invariants and acceptance checks pass.