Forward SMS content to Feishu notifications

[leonfox28]

Summary

• send one independent Feishu message for every newly persisted inbound SMS
• include the transport-neutral sender and complete Unicode/multiline body
• preserve one count-only summary per sync cycle for non-Feishu channels
• isolate per-message timeouts and failures while suppressing replay duplicates
• revalidate complete multipart bodies before persistence

Safety and compatibility

• no API, Web, SSE, schema, generated-source, provider-endpoint, or hardware boundary changes
• SMS bodies remain private to configured Feishu delivery and do not enter logs or errors
• automated validation used synthetic transports only; it sent no real SMS, Feishu, RF, modem-write, or HIL action

Verification

• go test -count=1 ./internal/application/messaging ./internal/application/notification
• affected packages under go test -race -count=1
• make check-format
• make verify-generated
• make lint
• make test
• make check-docs
• git diff --check

[leonfox28]

Review completed: no feature-blocking findings. The per-SMS Feishu delivery, replay suppression, provider isolation, bounded independent contexts, privacy boundary, multipart validation, and co-located tests match the approved contract.

CI note: compose-contract and all three image builds passed. The verify job fails only at govulncheck because the repository baseline pins Go 1.26.5; the latest main run fails on the same five standard-library advisories, all fixed in Go 1.26.6. This PR does not change the toolchain, so that separate baseline upgrade is intentionally not mixed into this feature change.