perf: bound DM subsystem network concurrency

Replaces unbounded Promise.all with pMap and RELAY_BACKGROUND_CONCURRENCY (3) in js/nostr/dmSignalEvents.js and js/services/dmNostrService.js to prevent network saturation. Includes context logs and daily performance report.

Co-authored-by: PR0M3TH3AN <[email protected]>

context/CONTEXT_2026-02-17.md

@@ -0,0 +1,20 @@
+# Context - Perf Agent - 2026-02-17
+
+## Goal
+Improve application responsiveness by bounding concurrency in background network tasks, specifically for DM signal events and DM service operations.
+
+## Scope
+- `js/nostr/dmSignalEvents.js`: Fix unbounded `Promise.all` in `publishDmReadReceipt` and `publishDmTypingIndicator`.
+- `js/services/dmNostrService.js`: Fix unbounded `Promise.all` in `connect` and `publishSignedEvent`.
+- `content/docs/guides/upload-content.md`: Fix documentation port number (5500 -> 3000).
+
+## Assumptions
+- `pMap` utility works as expected.
+- `RELAY_BACKGROUND_CONCURRENCY` (3) is an appropriate limit for these operations.
+
+## Definition of Done
+- All `Promise.all` usages in targeted functions are replaced with `pMap` with concurrency limits.
+- `npm run lint` passes.
+- `npm run test:dm:unit` passes.
+- `npm run test:dm:integration` passes.
+- `content/docs/guides/upload-content.md` is updated.