feat: multi-persona support (single Cortex, multiple users)

- Add cortex/persona.py: ContextVar-based per-request routing with
  path traversal protection and persona validation
- Migrate inara/ → personas/inara/ (git history preserved via git mv)
- config.py: add personas_root(), inara_path() delegates to personas/inara
- All 14 settings.inara_path() call sites replaced with persona_path()
- ChatRequest + OrchestrateRequest: add persona field (default: "inara")
  with validation at request entry before any processing
- memory_distiller: add optional persona param for future per-persona distill
- cron_runner/tools/cron: stamp persona on jobs, prefix APScheduler IDs
  (persona:job_id) to prevent collisions across personas
- scheduler: _load_user_crons() iterates all personas at startup

Adding a new persona: create personas/<name>/ with IDENTITY.md + SOUL.md.
Auth: handled at nginx level (inject X-Cortex-Persona header per subdomain).
Future: persona maps to Aether account_id_random for full integration.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/config.py

@@ -27,7 +27,8 @@ class Settings(BaseSettings):
     agent_name: str = "Inara"
     user_name: str = "Scott"
 
-    inara_dir: Path = Path("../inara")
+    personas_dir: Path = Path("../personas")
+    inara_dir: Path = Path("../personas/inara")  # legacy — use personas_dir
     sessions_dir: Path = Path("./data/sessions")
     default_model: str = "claude-sonnet-4-6"
     default_tier: int = 2
@@ -39,6 +40,11 @@ class Settings(BaseSettings):
     timeout_gemini: int = 120   # frequently slow under load
     timeout_local: int = 300    # local models may need to load first
 
+    # Google Chat
+    # JWT audience (aud) claim to verify on inbound webhook requests.
+    # Google Chat sets aud = the Google Cloud project number (e.g. "741112865538").
+    # Set to "" to disable verification (dev/testing only).
+    google_chat_audience: str = ""
     # Google Chat must receive a response within 30s or shows an error to the user
     google_chat_timeout: int = 25
     # Backend forced for Google Chat — Claude is more reliable within the 25s deadline
@@ -68,11 +74,15 @@ class Settings(BaseSettings):
 
     model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
 
+    def personas_root(self) -> Path:
+        """Resolve personas_dir relative to this file's location if not absolute."""
+        if self.personas_dir.is_absolute():
+            return self.personas_dir
+        return (Path(__file__).parent / self.personas_dir).resolve()
+
     def inara_path(self) -> Path:
-        """Resolve inara_dir relative to this file's location if not absolute."""
-        if self.inara_dir.is_absolute():
-            return self.inara_dir
-        return (Path(__file__).parent / self.inara_dir).resolve()
+        """Legacy helper — returns the inara persona directory. Prefer persona_path()."""
+        return self.personas_root() / "inara"
 
     def sessions_path(self) -> Path:
         """Resolve sessions_dir relative to this file's location if not absolute."""