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/researcher/README.md

@@ -0,0 +1,32 @@
+# Researcher Hand
+
+Autonomous deep researcher -- exhaustive investigation, cross-referencing, fact-checking, and structured reports.
+
+## Configuration
+
+| Field | Value |
+|-------|-------|
+| Category | `productivity` |
+| Agent | `researcher-hand` |
+| Routing | `deep research`, `systematic review`, `landscape analysis`, `exhaustive investigation` |
+
+## Integrations
+
+None required.
+
+## Settings
+
+- **Research Depth** -- `quick` (5-10 sources), `thorough` (20-30), `exhaustive` (50+)
+- **Output Style** -- `brief`, `detailed`, `academic`, `executive`
+- **Source Verification** -- Cross-check claims across multiple sources (default: on)
+- **Max Sources** -- `10`, `30`, `50`, `unlimited`
+- **Auto Follow-Up** -- Research follow-up questions discovered during investigation (default: on)
+- **Save Research Log** -- Save detailed search queries and source notes (default: off)
+- **Citation Style** -- `inline_url`, `footnotes`, `academic_apa`, `numbered`
+- **Language** -- `english`, `spanish`, `french`, `german`, `chinese`, `japanese`, `auto`
+
+## Usage
+
+```bash
+librefang hand run researcher
+```