feat(learn): Minimalist memory format v3.0 - 60% size reduction

BREAKING CHANGE: New compact entry format
- Header: `## {P|G}: {Title}` (P=Pattern, G=Gotcha)
- Metadata: `@YYYY-MM-DD #tag1 #tag2 | source:confidence[:reinforced]`
- Max 3 inline tags, no separators, no statistics section

Removed verbose fields: Discovered, Source, Confidence, Trigger
Statistics now calculated dynamically by /learn:status

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

CHANGELOG.md

@@ -5,6 +5,28 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [3.0.0] - 2026-01-07
+
+### Changed (BREAKING)
+- **Minimalist memory format**: ~60% reduction in file size
+  - Old: `### Titlu` + 3 metadata lines + separators (~600 char/entry)
+  - New: `## P: Titlu` + 1 metadata line (~200 char/entry)
+- **Header format**: `## {P|G}: {Titlu}` (P=Pattern, G=Gotcha)
+- **Metadata format**: `@YYYY-MM-DD #tag1 #tag2 | source:confidence[:reinforced]`
+- **Tags**: Inline with `#`, max 3 per entry
+- **Statistics**: Removed from files, calculated dynamically by `/learn:status`
+
+### Removed
+- `**Discovered**:`, `**Source**:`, `**Confidence**:`, `**Trigger**:` fields
+- `---` separators between entries
+- `## Domain Statistics` section from memory files
+- `(feature: ...)` context notation
+
+### Migration
+- Entries in v2.x format are read normally
+- Auto-converted to v3.0 format on first edit
+- Run `/learn:analyze` to test new format
+
 ## [2.1.0] - 2026-01-06
 
 ### Added