feat: stats and achievements (#45)

### Explanation

_No response_

### Issue

Closes #39

### Attestations

- [ ] I have read and agree to the [Code of Conduct](https://docs.nhcarrigan.com/community/coc/)
- [ ] I have read and agree to the [Community Guidelines](https://docs.nhcarrigan.com/community/guide/).
- [ ] My contribution complies with the [Contributor Covenant](https://docs.nhcarrigan.com/dev/covenant/).

### Dependencies

- [ ] I have pinned the dependencies to a specific patch version.

### Style

- [ ] I have run the linter and resolved any errors.
- [ ] My pull request uses an appropriate title, matching the conventional commit standards.
- [ ] My scope of feat/fix/chore/etc. correctly matches the nature of changes in my pull request.

### Tests

- [ ] My contribution adds new code, and I have added tests to cover it.
- [ ] My contribution modifies existing code, and I have updated the tests to reflect these changes.
- [ ] All new and existing tests pass locally with my changes.
- [ ] Code coverage remains at or above the configured threshold.

### Documentation

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### Versioning

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Reviewed-on: #45
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

src/lib/types/achievements.ts

@@ -0,0 +1,93 @@
+export interface AchievementUnlockedEvent {
+  achievement: {
+    id: AchievementId;
+    name: string;
+    description: string;
+    icon: string;
+    unlocked_at: string | null;
+  };
+}
+
+export type AchievementId =
+  // Token Milestones
+  | "FirstSteps" // 1,000 tokens
+  | "GrowingStrong" // 10,000 tokens
+  | "BlossomingCoder" // 100,000 tokens
+  | "TokenMaster" // 1,000,000 tokens
+  // Code Generation
+  | "HelloWorld" // First code block
+  | "CodeWizard" // 100 code blocks
+  | "ThousandBlocks" // 1,000 code blocks
+  // File Operations
+  | "FileManipulator" // 10 files edited
+  | "FileArchitect" // 100 files edited
+  // Conversation milestones
+  | "ConversationStarter" // 10 messages
+  | "ChattyKathy" // 100 messages
+  | "Conversationalist" // 1,000 messages
+  // Tool usage
+  | "Toolsmith" // 5 different tools
+  | "ToolMaster" // 10 different tools
+  // Time-based achievements
+  | "EarlyBird" // Started session 5-7 AM
+  | "NightOwl" // Coding after midnight
+  | "AllNighter" // Worked 2-5 AM
+  | "WeekendWarrior" // Coding on weekend
+  | "DedicatedDeveloper" // 30 days in a row
+  // Search and exploration
+  | "Explorer" // 50 searches
+  | "MasterSearcher" // 500 searches
+  // Session achievements
+  | "QuickSession" // Productive session < 5 min
+  | "FocusedWork" // 30 min session
+  | "DeepDive" // 2 hour session
+  | "MarathonSession" // 5+ hour session
+  // Special achievements
+  | "FirstMessage" // First message sent
+  | "FirstTool" // First tool used
+  | "FirstCodeBlock" // First code generated
+  | "FirstFileEdit" // First file edit
+  | "Polyglot" // 5+ languages in one session
+  | "SpeedCoder" // 10 code blocks in 10 minutes
+  | "ClaudeConnoisseur" // Used all Claude models
+  | "MarathonCoder" // 10k tokens in one session
+  // Relationship & Greetings
+  | "GoodMorning" // Said good morning
+  | "GoodNight" // Said good night
+  | "ThankYou" // Said thank you
+  | "LoveYou" // Said love you
+  // Personality & Fun
+  | "EmojiUser" // Used 20+ emojis
+  | "CapsLock" // ALL CAPS MESSAGE
+  | "QuestionMaster" // Asked 50 questions
+  | "PleaseAndThankYou" // Polite user
+  // Git & Development
+  | "CommitMaster" // 100 commits
+  | "PRO" // Created 10 PRs
+  | "Reviewer" // Reviewed 10 PRs
+  | "IssueTracker" // Created 25 issues
+  | "GitGuru" // Used git commands
+  // Tool Mastery
+  | "BashMaster" // Used bash 100 times
+  | "FileExplorer" // Searched files 100 times
+  | "SearchExpert" // Advanced searches
+  | "AgentCommander" // Used task agents
+  | "MCPMaster"; // Used MCP tools
+
+export interface Achievement {
+  id: AchievementId;
+  name: string;
+  description: string;
+  icon: string;
+  rarity: "common" | "rare" | "epic" | "legendary";
+  unlocked: boolean;
+  unlockedAt?: Date;
+  progress?: number;
+  maxProgress?: number;
+}
+
+export interface AchievementCategory {
+  name: string;
+  description: string;
+  achievements: Achievement[];
+}