Move Odin renderer into gui/ with per-project Makefiles

Each sub-project (gui, api, infra) now owns its own Makefile, and the
root Makefile is a lean delegator for the base commands (run, build,
test, clean, fmt). Odin source, deps, and web assets live under gui/
(gui/src, gui/lib, gui/www), with scripts kept under gui/scripts for
build tooling only.

.gitea/workflows/ci.yml

@@ -34,10 +34,8 @@ jobs:
         with:
           filters: |
             odin:
-              - 'src/**'
-              - 'lib/**'
+              - 'gui/**'
               - 'scripts/**'
-              - 'odinfmt.json'
             api:
               - 'api/**'
 
@@ -65,14 +63,10 @@ jobs:
           fi
 
       - name: Run Odin unit tests
-        run: |
-          mkdir -p lib/local
-          odin test src -collection:lib=lib/local
+        run: make -C gui test
 
       - name: Verify build
-        run: |
-          mkdir -p bin
-          odin build src -collection:lib=lib/local -o:speed -out:bin/desi_explorer
+        run: make -C gui build
 
   api:
     name: API unit tests and lint