feat: multi-user/multi-persona support with two-level home directory layout

Restructures persona storage from a flat personas/{name}/ layout to
home/{username}/persona/{name}/, mirroring Linux home directories.

Changes:
- persona.py: two ContextVars (user + persona), Linux-style name validation,
  set_context(), get_user(), get_persona(), validate(), list_users(),
  list_user_personas(); persona_path() takes (username, name)
- config.py: replaces personas_dir with home_dir + home_root()
- git mv personas/inara → home/scott/persona/inara (history preserved)
- home/holly/persona/tina/: Holly's persona stub added
- cron_runner.py: all storage functions take (username, persona) params
- tools/cron.py: stamps user + persona on jobs; APScheduler IDs are
  {user}:{persona}:{job_id} to prevent collisions across users
- memory_distiller.py: distill_short/mid/long take (username, persona);
  added missing Path + settings imports
- scheduler.py: _load_user_crons() iterates home/*/persona/* (two-level)
- routers/chat.py, orchestrator.py: user field added; set_context() called
- tests/conftest.py: home_root fixture with two-level structure;
  patches home_dir instead of personas_dir
- tests/test_persona.py: fully rewritten for two-level API
- tests/test_api_files.py: updated fixture name and path
- .env.default: documents HOME_DIR setting; scrubs stale API key
- CLAUDE.md, README.md: directory maps updated for new layout

All 80 tests pass.

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

home/scott/persona/inara/USER.md

@@ -0,0 +1,69 @@
+# USER.md — Scott Idem
+
+## Identity
+
+| Field      | Value |
+|------------|-------|
+| Name       | Scott Idem |
+| Pronouns   | he/him |
+| Location   | Silver Spring (Wheaton), MD |
+| Timezone   | America/New_York (EST/EDT) |
+| Birthday   | August 11, 1980 |
+| Origin     | Little Washington, NC |
+
+---
+
+## Organizations
+
+- **One Sky IT (OSIT):** Professional / Business. IT consulting, software development.
+- **Danger Zone (DgrZone):** Personal / Home. Homelab, personal projects.
+
+---
+
+## What He Cares About
+
+- **Aether Platform:** His primary software project — a multi-tenant business management system
+  built for OSIT clients. He is proud of the architecture (especially the MariaDB schema).
+- **Cortex:** The multi-agent orchestration layer he is building. I am its primary resident agent.
+- **Homelab:** WireGuard mesh, pfSense, VLANs, Syncthing, Docker, self-hosted everything.
+- **Clients:** Precon Events, IDAA, BGH, CMSC, LCI, AACC.
+
+---
+
+## Working Style
+
+- 20+ years in IT. Broad expertise: networking, databases, systems, programming.
+- Patient, curious, thoughtful. Focus is a challenge — benefits from structured assistance.
+- **Motivation:** Helping people matters more than money.
+- **Communication:** Casual, peer-to-peer technical discussion. No corporate tone.
+- Night owl — late-night sessions are normal and common.
+
+---
+
+## Coding Preferences
+
+- **Languages:** Python (strongly preferred). JS/TS for frontend only.
+- **Casing:** `snake_case` or `Snake_Case`. No `camelCase`. Dashes acceptable when
+  technically required (URLs, package names, visual clarity).
+- **Indentation:** 4 spaces. No tabs.
+- **Datetime format:** `YYYY-MM-DD_HHMMSS` for filenames and logs.
+- **Editors:** vim (terminal), VS Code (GUI)
+- **Frontend stack:** SvelteKit 5 + Tailwind 4 + Skeleton UI + Lucide icons
+
+---
+
+## Personal Notes
+
+- Has twin brothers (~2 years younger) in CS/Engineering.
+- Solar array installed February 2026 — 10kW peak generation.
+- Named his homelab org "Danger Zone" (Top Gun reference).
+- Naming things well matters to him — Aether → Cortex → Inara is an intentional arc.
+
+---
+
+## What Works
+
+- Treat him as a peer expert. No hand-holding.
+- Be direct and concise. Skip preamble.
+- Explain destructive actions before doing them.
+- Casual tone is correct; formality is not.