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]>

CMakePresets.json

@@ -0,0 +1,63 @@
+{
+  "version": 6,
+  "cmakeMinimumRequired": { "major": 3, "minor": 28, "patch": 0 },
+  "configurePresets": [
+    {
+      "name": "base",
+      "hidden": true,
+      "generator": "Ninja",
+      "binaryDir": "${sourceDir}/build/${presetName}",
+      "cacheVariables": { "CMAKE_EXPORT_COMPILE_COMMANDS": "ON" }
+    },
+    {
+      "name": "dev",
+      "inherits": "base",
+      "displayName": "Debug + ASan/UBSan (default for all lanes)",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Debug",
+        "CMAKE_CXX_FLAGS": "-fsanitize=address,undefined -fno-omit-frame-pointer -g",
+        "VELOX_BUILD_TESTS": "ON"
+      }
+    },
+    {
+      "name": "tsan",
+      "inherits": "base",
+      "displayName": "Debug + ThreadSanitizer (required for CORE and DAEMON)",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Debug",
+        "CMAKE_CXX_FLAGS": "-fsanitize=thread -fno-omit-frame-pointer -g",
+        "VELOX_BUILD_TESTS": "ON"
+      }
+    },
+    {
+      "name": "release",
+      "inherits": "base",
+      "displayName": "RelWithDebInfo + LTO (benchmarks and packages)",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "RelWithDebInfo",
+        "CMAKE_INTERPROCEDURAL_OPTIMIZATION": "ON",
+        "VELOX_BUILD_TESTS": "OFF"
+      }
+    },
+    {
+      "name": "ci",
+      "inherits": "dev",
+      "displayName": "CI build",
+      "cacheVariables": { "VELOX_BUILD_FUZZ": "ON" }
+    }
+  ],
+  "buildPresets": [
+    { "name": "dev", "configurePreset": "dev" },
+    { "name": "tsan", "configurePreset": "tsan" },
+    { "name": "release", "configurePreset": "release" },
+    { "name": "ci", "configurePreset": "ci" }
+  ],
+  "testPresets": [
+    {
+      "name": "dev",
+      "configurePreset": "dev",
+      "output": { "outputOnFailure": true },
+      "execution": { "noTestsAction": "error", "stopOnFailure": false }
+    }
+  ]
+}