feat: rename agent-install parameters for clarity

- Change --path → --source (much clearer purpose)
- Change --target → --destination (more intuitive)
- Update all code references and documentation
- Add advanced parameter examples to installation guide
- Keep short aliases: -s for --source, -t for --destination

Parameters are now much more self-explanatory:
- --source: where to find the agent YAML
- --destination: where to install the compiled agent

src/modules/bmb/workflows/create-agent/installation-guide.md

@@ -50,6 +50,22 @@ npx bmad-method agent-install    # Works anywhere without cloning
 - `bmad install` → "Compile Agents" (rebuild all agents)
 - `bmad install` → "Quick Update" (during upgrades)
 
+**Advanced Parameters**:
+
+```bash
+# Install specific agent file
+npx bmad-method agent-install --source ./my-agent.agent.yaml
+
+# Use default configuration (no prompts)
+npx bmad-method agent-install --defaults
+
+# Install to specific destination
+npx bmad-method agent-install --destination ./my-project
+
+# Combine parameters
+npx bmad-method agent-install --source ./my-agent.agent.yaml --defaults --destination ./my-project
+```
+
 **When to use which**:
 
 - **Option 1**: Best for new agents or when you want custom persona names