scaffold: project structure, wire contract, roadmap and agent briefs

Lays out Velox Download Manager (IDM-class download manager for Ubuntu
26.04) as a monorepo ready for parallel lane development. No implementation
code by design.

- docs/: architecture, roadmap M0-M7, IDM-parity GUI spec, engine design,
  Firefox extension spec, risks/spikes, packaging
- contracts/: wire-contract skeleton (JSON Schema + fixture templates) —
  the single synchronization point between lanes
- docs/agents/: one brief per lane (PROTO, CORE, DAEMON, GUI, EXT, PKG/QA)
  with owned directories, build order and definition of done
- CLAUDE.md: rules of engagement — lane ownership, layering, non-negotiables
- CMake scaffolding with dev/tsan/release/ci presets

Two environment findings shape the design: Firefox here is the Mozilla snap
(native-messaging risk, so the extension carries a loopback-WebSocket
fallback), and Wayland forbids passive clipboard monitoring (so clipboard
capture is explicit-action-first).

Co-Authored-By: Claude Opus 5 <[email protected]>

contracts/schema/types/TaskSummary.schema.json

@@ -0,0 +1,44 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://velox.dev/schema/types/TaskSummary.schema.json",
+  "title": "TaskSummary",
+  "description": "One row of the main download list. Everything the GUI table needs, and nothing more. TEMPLATE — lane PROTO owns the final shape.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["taskId", "filename", "state", "createdAt"],
+  "properties": {
+    "taskId":       { "type": "string", "format": "uuid" },
+    "filename":     { "type": "string", "maxLength": 255 },
+    "saveDir":      { "type": "string" },
+    "url":          { "type": "string", "format": "uri" },
+    "effectiveUrl": { "type": "string", "format": "uri" },
+    "sizeBytes":    { "type": ["integer", "null"], "minimum": 0, "description": "null when the server did not report a length" },
+    "downloadedBytes": { "type": "integer", "minimum": 0 },
+    "state": {
+      "type": "string",
+      "enum": ["new", "probing", "queued", "connecting", "downloading", "paused",
+               "retry_wait", "assembling", "verifying", "complete", "failed", "cancelled"]
+    },
+    "speedBps":     { "type": "integer", "minimum": 0 },
+    "etaSeconds":   { "type": ["integer", "null"], "minimum": 0 },
+    "resumable":    { "type": "boolean" },
+    "segments":     { "type": "integer", "minimum": 1, "maximum": 32 },
+    "categoryId":   { "type": ["string", "null"] },
+    "queueId":      { "type": ["string", "null"] },
+    "queuePosition":{ "type": ["integer", "null"], "minimum": 0, "description": "the Q column" },
+    "description":  { "type": "string", "maxLength": 1024 },
+    "createdAt":    { "type": "string", "format": "date-time" },
+    "lastTryAt":    { "type": ["string", "null"], "format": "date-time" },
+    "completedAt":  { "type": ["string", "null"], "format": "date-time" },
+    "error": {
+      "type": ["object", "null"],
+      "additionalProperties": false,
+      "properties": {
+        "code":       { "type": "integer" },
+        "message":    { "type": "string" },
+        "httpStatus": { "type": ["integer", "null"] },
+        "retryable":  { "type": "boolean" }
+      }
+    }
+  }
+}