docs: add README for every subdirectory

33 agent READMEs, 14 hand READMEs, 2 plugin READMEs
(echo-memory + hooks), and 2 skill READMEs
(custom-skill-prompt + custom-skill-python).

Each README documents the component's purpose, configuration,
and usage based on its TOML definition.

hands/browser/README.md

@@ -0,0 +1,30 @@
+# Browser Hand
+
+Autonomous web browser -- navigates sites, fills forms, clicks buttons, and completes multi-step web tasks with user approval for purchases.
+
+## Configuration
+
+| Field | Value |
+|-------|-------|
+| Category | `productivity` |
+| Agent | `browser-hand` |
+| Routing | `open website`, `navigate to`, `fill form`, `click button`, `web login`, `browser automation` |
+
+## Integrations
+
+- **Python 3** -- Required for Playwright browser automation library.
+- **Chromium** (optional) -- A Chromium-based browser; Playwright can install its own if none found.
+
+## Settings
+
+- **Headless Mode** -- Run browser without a visible window (default: on)
+- **Purchase Approval** -- Require confirmation before purchases (default: on)
+- **Max Pages Per Task** -- Navigation limit per task (`10`, `20`, `50`)
+- **Default Wait After Action** -- Page settle time (`auto`, `1s`, `3s`)
+- **Screenshot After Actions** -- Auto-screenshot after every action (default: off)
+
+## Usage
+
+```bash
+librefang hand run browser
+```