docs: restructure documentation into multilevel directory layout

New structure: docs/ split into 11 subdirectories (getting-started/,
agents/, providers/, sidecar/, multi-machine/, plugins/, config/,
production/, architecture/, contributing/, pro/).

New files:
- docs/README.md: navigation index with audience table
- docs/getting-started/quickstart.md: install, build, first session
- docs/config/ref-settings.md: all env vars, config files, databases
- docs/architecture/overview.md: split from architecture.md (>300 lines)
- docs/pro/README.md: Pro edition overview
- docs/pro/features/analytics.md: analytics dashboard docs
- docs/pro/features/cost-intelligence.md: budget + router docs

Remaining docs being written by background agents — will be committed
in follow-up when complete.

docs/pro/README.md

@@ -0,0 +1,110 @@
+# Agents Orchestrator Pro Edition
+
+> This documentation covers Pro edition features available in the agents-orchestrator/agents-orchestrator private repository.
+
+## Overview
+
+Agents Orchestrator Pro extends the open-source community edition with commercial features for teams and organizations that need deeper analytics, cost controls, persistent agent knowledge, and a plugin marketplace. Pro features are architecturally isolated from the community codebase, implemented as a Tauri plugin crate and a separate Svelte module tree.
+
+## Feature Summary
+
+| Feature | Description | Documentation |
+|---------|-------------|---------------|
+| Analytics Dashboard | Session cost trends, model usage breakdown, daily statistics | [analytics.md](features/analytics.md) |
+| Budget Governor | Per-project monthly token budgets with soft/hard limits | [cost-intelligence.md](features/cost-intelligence.md) |
+| Smart Model Router | Cost-aware model selection with routing profiles | [cost-intelligence.md](features/cost-intelligence.md) |
+| Persistent Agent Memory | Per-project knowledge fragments with FTS5 search and TTL | [knowledge-base.md](features/knowledge-base.md) |
+| Codebase Symbol Graph | Regex-based symbol extraction and caller lookup | [knowledge-base.md](features/knowledge-base.md) |
+| Git Context Injection | Branch, commit, and diff context for agent prompts | [git-integration.md](features/git-integration.md) |
+| Branch Policy | Session-level protection for sensitive branches | [git-integration.md](features/git-integration.md) |
+| Plugin Marketplace | Curated plugin catalog with install/update lifecycle | [marketplace/README.md](marketplace/README.md) |
+
+## Architecture
+
+Pro features are separated from the community codebase at two layers:
+
+### Rust Backend: `agor-pro` Tauri Plugin Crate
+
+The `agor-pro` crate is a standalone Tauri plugin located at `crates/agor-pro/` in the private repository. It contains all Pro-specific Rust logic: SQLite tables, commands, and business rules.
+
+The crate exposes a single entry point:
+
+```rust
+pub fn init() -> TauriPlugin<tauri::Wry> { ... }
+```
+
+### Svelte Frontend: `src/lib/commercial/`
+
+Pro UI components live under `src/lib/commercial/` with their own adapters and stores. Community components never import from this path. The commercial module tree mirrors the community structure:
+
+```
+src/lib/commercial/
+  adapters/        -- IPC bridges for pro commands
+  components/      -- Pro-specific UI (analytics, budgets, marketplace)
+  stores/          -- Pro-specific state
+```
+
+## Feature Flag
+
+Pro features are gated at both compile time and runtime.
+
+### Cargo Feature Flag
+
+The `pro` feature flag controls Rust compilation:
+
+```bash
+# Community build (default)
+cargo build -p bterminal
+
+# Pro build
+cargo build -p bterminal --features pro
+```
+
+When `--features pro` is active, `lib.rs` registers the plugin:
+
+```rust
+#[cfg(feature = "pro")]
+app.handle().plugin(agor_pro::init());
+```
+
+### Frontend Edition Flag
+
+The `AGOR_EDITION` environment variable controls frontend feature visibility:
+
+```bash
+# Community build (default)
+AGOR_EDITION=community npm run tauri build
+
+# Pro build
+AGOR_EDITION=pro npm run tauri build
+```
+
+Svelte components check this at module level:
+
+```typescript
+const isPro = import.meta.env.VITE_AGOR_EDITION === 'pro';
+```
+
+## IPC Pattern
+
+All Pro commands follow the Tauri plugin IPC convention. Commands are namespaced under `plugin:agor-pro`:
+
+```typescript
+import { invoke } from '@tauri-apps/api/core';
+
+const summary = await invoke('plugin:agor-pro|pro_analytics_summary', {
+  period: 30,
+});
+```
+
+Command names use the `pro_` prefix consistently. Arguments are passed as a single object. Return types are JSON-serialized Rust structs with `#[serde(rename_all = "camelCase")]`.
+
+## Error Handling
+
+Pro commands return `Result<T, String>` on the Rust side. The frontend adapters in `src/lib/commercial/adapters/` wrap `invoke()` calls and surface errors through the standard notification system. When the Pro plugin is not loaded (community build), invoke calls fail with a predictable `plugin not found` error that the adapters catch and handle silently.
+
+## Database
+
+Pro features use a dedicated SQLite database at `~/.local/share/bterminal/agor_pro.db` (WAL mode, 5s busy timeout). This keeps Pro data isolated from community tables. The `pro_budgets` and `pro_budget_log` tables are created on plugin init via migrations.
+
+Read-only access to community tables (e.g., `session_metrics` in `sessions.db`) is done through a separate read-only connection.