feat: implement --with/--without selective install flags (#679)

Add agent: and skill: component families to the install component
catalog, enabling fine-grained selective install via CLI flags:

  ecc install --profile developer --with lang:typescript --without capability:orchestration
  ecc install --with lang:python --with agent:security-reviewer

Changes:
- Add agent: family (9 entries) and skill: family (10 entries) to
  manifests/install-components.json for granular component addressing
- Update install-components.schema.json to accept agent: and skill:
  family prefixes
- Register agent and skill family prefixes in COMPONENT_FAMILY_PREFIXES
  (scripts/lib/install-manifests.js)
- Add 41 comprehensive tests covering CLI parsing, request normalization,
  component catalog validation, plan resolution, target filtering,
  error handling, and end-to-end install with --with/--without flags

Closes #470

scripts/lib/install-manifests.js

@@ -10,6 +10,8 @@ const COMPONENT_FAMILY_PREFIXES = {
   language: 'lang:',
   framework: 'framework:',
   capability: 'capability:',
+  agent: 'agent:',
+  skill: 'skill:',
 };
 const LEGACY_COMPAT_BASE_MODULE_IDS_BY_TARGET = Object.freeze({
   claude: [