v2.1: Unify skills and slash commands pattern (#5)

* v2.1: Unify skills and slash commands pattern

Following the new Claude Code standard where skills and slash commands
are merged into a single unified pattern:

- Convert commands to skills: /daily-workflow, /weekly-review, /push, /onboard
- Each skill has SKILL.md with frontmatter (name, description, allowed-tools)
- Skills can be invoked with /skill-name OR auto-discovered by Claude
- Remove deprecated .claude/commands/ directory
- Update all documentation to reference new unified pattern
- Update agents to reference skills instead of commands
- Update CLAUDE.md with unified skills table

This aligns with Claude Code 2.1+ where skills and slash commands
share the same features and invocation patterns.

* Simplify skill names: daily-workflow → daily, weekly-review → weekly

Rename verbose skill folders and names to shorter, cleaner invocations:
- daily-workflow/ → daily/ (invoked with /daily)
- weekly-review/ → weekly/ (invoked with /weekly)

Update all references across documentation, agents, and skill files
to use consistent short command names.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

vault-template/.claude/agents/note-organizer.md

@@ -68,6 +68,6 @@ Wait for user confirmation before making changes.
 ## Integration
 
 Works well with:
-- `/onboard` command for initial context
+- `/onboard` skill for initial context
 - Productivity Coach output style for guidance
 - Weekly review workflow for regular maintenance