feat: rework auth model with UserToken and Daedalus/Pallas integration

- Rename MCPToken to UserToken across models, views, and tests
- Update URL names from mcp-token-* to token-*
- Add Daedalus/Pallas integration design doc (v2)
- Switch docker-compose to build local mnemosyne:local image via shared
  build config instead of pulling from git.helu.ca

docker-compose.yaml

@@ -69,6 +69,16 @@ x-logging: &default-logging
     max-size: "10m"
     max-file: "5"
 
+# -----------------------------------------------------------------------------
+# Shared build config — build the Mnemosyne image locally from ./Dockerfile
+# instead of pulling from git.helu.ca. All four Mnemosyne services
+# (init/app/mcp/worker) share `image: mnemosyne:local`, so Compose builds
+# once and reuses the resulting image across them.
+# -----------------------------------------------------------------------------
+x-mnemosyne-build: &mnemosyne-build
+  context: .
+  dockerfile: Dockerfile
+
 
 services:
   # ── Init sidecar: one-shot Postgres migrate + collectstatic + library-type seed. Runs on
@@ -88,8 +98,8 @@ services:
   # This sidecar only needs Postgres, Neo4j, static files, and logging env —
   # no S3, no Celery, no LLM encryption key. Keep it that way.
   init:
-    image: git.helu.ca/r/mnemosyne:latest
-    pull_policy: always
+    image: mnemosyne:local
+    build: *mnemosyne-build
     command: ["init"]
     environment:
       # Django core (settings import)
@@ -124,8 +134,8 @@ services:
   # Celery tasks (hence CELERY_BROKER_URL is required here too — Django is
   # the producer, the worker is the consumer).
   app:
-    image: git.helu.ca/r/mnemosyne:latest
-    pull_policy: always
+    image: mnemosyne:local
+    build: *mnemosyne-build
     command: ["web"]
     environment:
       # Django core
@@ -220,8 +230,8 @@ services:
   # the S3 key here only matters if someone exploits a write path in the
   # future — keep the credential scoped to read-only in your secret manager.
   mcp:
-    image: git.helu.ca/r/mnemosyne:latest
-    pull_policy: always
+    image: mnemosyne:local
+    build: *mnemosyne-build
     command: ["mcp"]
     environment:
       # Django core (ASGI still imports settings)
@@ -289,8 +299,8 @@ services:
   # backend. Does NOT need HTTP-layer settings (ALLOWED_HOSTS, CSRF, MCP auth)
   # or search tuning (the worker never serves queries).
   worker:
-    image: git.helu.ca/r/mnemosyne:latest
-    pull_policy: always
+    image: mnemosyne:local
+    build: *mnemosyne-build
     command: ["worker"]
     environment:
       # Django core (Celery imports settings)