feat: audit log, usage tracking UI, OpenAI orchestrator compaction, onboarding + docs

Tool audit log:
- Every orchestrator tool call logged to home/{user}/tool_audit/YYYY-MM-DD.jsonl
- Files panel sidebar: audit log group (collapsed), date-linked read-only table
- Admin endpoints: /api/audit/files, /api/audit/day, /api/audit/recent, /api/audit/stats
- Engine and model name recorded per entry

OpenAI orchestrator improvements:
- Context budget enforcement: 75% of model context_k (min 16k)
- Message compaction: truncates old tool results when approaching budget
- max_rounds respected per model config (intersected with server cap)

OpenRouter onboarding (setup.html, onboarding.py, app.js, settings.html):
- Step 3 of 3: /setup/model with curated model picker
- Chat banner for users on server-default model (informational, not alarmist)
- Settings quick-link card; /setup/model works standalone for existing users

Model registry + session store:
- set_role_config / get_role_config for per-role tool lists and system_append
- session_store: session rename, session name backfill endpoint

UI updates (app.js, index.html, style.css, local_llm.html):
- Role toggle in context panel
- Off-the-record mode
- Agent notes read-only viewer
- OPERATIONS.md loaded at T2+ in context

Documentation:
- HELP.md: full tool table, per-role tool sets, Agent Notes, usage tracking
- TOOLS.md: Agent Notes section, count corrected to 44
- ARCH__SYSTEM.md, ARCH__BACKENDS.md, MASTER.md updated to match reality
- CLAUDE.md: onboarding flow, documentation philosophy sections
- README.md: stack in practice, DeepSeek TUI mention, architecture diagram updated
- TODO__Agents.md: onboarding task completed with deviation notes

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

cortex/static/index.html

@@ -87,10 +87,10 @@
             <div class="ctx-section">
                 <div class="ctx-section-title">Context Tier</div>
                 <div class="ctx-row">
-                    <button class="ctx-btn" data-tier="1" id="tier-1" title="Minimal (~1.5k tokens)">T1</button>
-                    <button class="ctx-btn active" data-tier="2" id="tier-2" title="Standard (~5k tokens)">T2</button>
-                    <button class="ctx-btn" data-tier="3" id="tier-3" title="Extended (~15k tokens)">T3</button>
-                    <button class="ctx-btn" data-tier="4" id="tier-4" title="Full (~50k tokens)">T4</button>
+                    <button class="ctx-btn" data-tier="1" id="tier-1" title="Minimal — identity only (~1.5k tokens)">Min</button>
+                    <button class="ctx-btn active" data-tier="2" id="tier-2" title="Standard — memory + user profile (~5k tokens)">Std</button>
+                    <button class="ctx-btn" data-tier="3" id="tier-3" title="Extended — + last 2 sessions (~15k tokens)">Ext</button>
+                    <button class="ctx-btn" data-tier="4" id="tier-4" title="Full — + last 7 sessions (~50k tokens)">Full</button>
                 </div>
             </div>
             <div class="ctx-section">
@@ -108,6 +108,7 @@
                     <button class="ctx-btn" id="distill-mid-btn"   title="Summarize SHORT → MID memory (uses LLM)">Mid</button>
                     <button class="ctx-btn" id="distill-long-btn"  title="Integrate MID → LONG memory (uses LLM)">Long</button>
                     <button class="ctx-btn" id="distill-all-btn"   title="Run Short → Mid → Long in sequence">All</button>
+                    <button class="ctx-btn ctx-btn-danger" id="distill-rebuild-btn" title="⚠ Wipe Mid + Long memories and rebuild from session logs. Hand-edited content will be replaced.">Rebuild</button>
                 </div>
                 <div id="ctx-distill-status"></div>
                 <div id="ctx-schedule"></div>