v1.1.1: Blindaje de Fidelidad (D1–D5)

🔧 Fixed / Observability Hardening (Blindaje de Fidelidad D1–D5)

D4 — Error Source Integrity

• ScraperError::Download / Network now carry #[source] Box<dyn Error + Send + Sync>.
• CrawlError::Download and DownloadError::Network preserve #[source].
• From<DownloadError> for CrawlError keeps the full cause (wreq::Error → Connect/timeout) instead of .to_string().
• scrape_flow no longer flattens with .to_string(): failures retains the ScraperError and the orchestrator prints the source() chain (← cause).
• is_transient_error inspects the boxed error Display (broadened keywords) → 5xx/connect/timeout retries preserved.

D5 — Observable Connection Pooling

• client_id (stable {:p} pointer of the shared Arc<Client>) recorded as a span field in wreq_downloader::fetch and adapters::downloader::Downloader::download_once, and as an event field on the download log.
• Verified live: 15 asset downloads shared the same client_id → pool reuse confirmed (TLS handshake savings, socket-exhaustion protection).

D1–D3 — Stability

• D1: --download-concurrency 0 rejected at CLI (parse_download_concurrency) and clamped to 1 in with_download_concurrency → no buffer_unordered(0) deadlock.
• D2/D3: FileTraceLayer emits parent_id and a logical trace_id (W3C OTel / root-span / seed) → reconstructable trace tree.

Maintenance

• fix(clippy): parse_set_cookie uses ? instead of match (resolves clippy::question_mark on clippy 1.97 / CI).

Verification

• cargo clippy --all-targets --all-features -- -D warnings ✅ · unit+integration+behavioral tests ✅ · all-features tests ✅ · MCP handshake ✅ · CI conclusion: success.