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/collector/README.md

@@ -0,0 +1,32 @@
+# Collector Hand
+
+Autonomous intelligence collector -- monitors any target continuously with change detection and knowledge graphs.
+
+## Configuration
+
+| Field | Value |
+|-------|-------|
+| Category | `data` |
+| Agent | `collector-hand` |
+| Routing | `monitor changes`, `track updates`, `collect intelligence`, `osint`, `change detection` |
+
+## Integrations
+
+None required.
+
+## Settings
+
+- **Target Subject** -- What to monitor (company, person, technology, market, topic)
+- **Collection Depth** -- `surface`, `deep`, `exhaustive`
+- **Update Frequency** -- `hourly`, `every_6h`, `daily`, `weekly`
+- **Focus Area** -- `market`, `business`, `competitor`, `person`, `technology`, `general`
+- **Alert on Changes** -- Publish events on significant changes (default: on)
+- **Report Format** -- `markdown`, `json`, `html`
+- **Max Sources Per Cycle** -- `10`, `30`, `50`, `100`
+- **Track Sentiment** -- Analyze sentiment trends over time (default: off)
+
+## Usage
+
+```bash
+librefang hand run collector
+```