Story 18: Token-by-token streaming responses

- Backend: Added OllamaProvider::chat_stream() with newline-delimited JSON parsing
- Backend: Emit chat:token events for each token received from Ollama
- Backend: Added futures dependency and stream feature for reqwest
- Frontend: Added streamingContent state and chat:token event listener
- Frontend: Real-time token display with auto-scroll
- Frontend: Markdown and syntax highlighting support for streaming content
- Fixed all TypeScript errors (tsc --noEmit)
- Fixed all Biome warnings and errors
- Fixed all Clippy warnings
- Added comprehensive code quality documentation
- Added tsc --noEmit to verification checklist

Tested and verified:
- Tokens stream in real-time
- Auto-scroll works during streaming
- Tool calls interrupt streaming correctly
- Multi-turn conversations work
- Smooth performance with no lag

.living_spec/CODE_QUALITY_CHECKLIST.md

@@ -0,0 +1,227 @@
+# Code Quality Checklist
+
+This document provides a quick reference for code quality checks that MUST be performed before completing any story.
+
+## Pre-Completion Checklist
+
+Before asking for user acceptance in Step 4 (Verification), ALL of the following must pass:
+
+### Rust Backend
+
+```bash
+# 1. Run Clippy (linter)
+cd src-tauri
+cargo clippy --all-targets --all-features
+# Expected: 0 errors, 0 warnings
+
+# 2. Run cargo check (compilation)
+cargo check
+# Expected: successful compilation
+
+# 3. Run tests
+cargo test
+# Expected: all tests pass
+```
+
+**Result Required:** ✅ 0 errors, 0 warnings, all tests pass
+
+### TypeScript Frontend
+
+```bash
+# 1. Run TypeScript compiler check (type errors)
+npx tsc --noEmit
+# Expected: 0 errors
+
+# 2. Run Biome check (linter + formatter)
+npx @biomejs/biome check src/
+# Expected: 0 errors, 0 warnings
+
+# 3. Apply fixes if needed
+npx @biomejs/biome check --write src/
+npx @biomejs/biome check --write --unsafe src/  # for unsafe fixes
+
+# 4. Build
+npm run build
+# Expected: successful build
+```
+
+**Result Required:** ✅ 0 errors, 0 warnings, successful build
+
+## Common Biome Issues and Fixes
+
+### 1. `noExplicitAny` - No `any` types
+
+**Bad:**
+```typescript
+const handler = (data: any) => { ... }
+```
+
+**Good:**
+```typescript
+const handler = (data: { className?: string; children?: React.ReactNode; [key: string]: unknown }) => { ... }
+```
+
+### 2. `noArrayIndexKey` - Don't use array index as key
+
+**Bad:**
+```typescript
+{items.map((item, idx) => <div key={idx}>...</div>)}
+```
+
+**Good:**
+```typescript
+{items.map((item, idx) => <div key={`item-${idx}-${item.id}`}>...</div>)}
+```
+
+### 3. `useButtonType` - Always specify button type
+
+**Bad:**
+```typescript
+<button onClick={handler}>Click</button>
+```
+
+**Good:**
+```typescript
+<button type="button" onClick={handler}>Click</button>
+```
+
+### 4. `noAssignInExpressions` - No assignments in expressions
+
+**Bad:**
+```typescript
+onMouseOver={(e) => (e.currentTarget.style.background = "#333")}
+```
+
+**Good:**
+```typescript
+onMouseOver={(e) => {
+  e.currentTarget.style.background = "#333";
+}}
+```
+
+### 5. `useKeyWithMouseEvents` - Add keyboard alternatives
+
+**Bad:**
+```typescript
+<button onMouseOver={handler} onMouseOut={handler2}>...</button>
+```
+
+**Good:**
+```typescript
+<button 
+  onMouseOver={handler} 
+  onMouseOut={handler2}
+  onFocus={handler}
+  onBlur={handler2}
+>...</button>
+```
+
+### 6. `useImportType` - Import types with `import type`
+
+**Bad:**
+```typescript
+import { Message, Config } from "./types";
+```
+
+**Good:**
+```typescript
+import type { Message, Config } from "./types";
+```
+
+## Common Clippy Issues and Fixes
+
+### 1. Unused variables
+
+**Bad:**
+```rust
+} catch (e) {
+```
+
+**Good:**
+```rust
+} catch (_e) {  // prefix with underscore
+```
+
+### 2. Dead code warnings
+
+**Option 1:** Remove the code if truly unused
+
+**Option 2:** Mark as allowed if used conditionally
+```rust
+#[allow(dead_code)]
+struct UnusedStruct {
+    field: String,
+}
+```
+
+### 3. Explicit return
+
+**Bad:**
+```rust
+fn get_value() -> i32 {
+    return 42;
+}
+```
+
+**Good:**
+```rust
+fn get_value() -> i32 {
+    42
+}
+```
+
+## Quick Verification Script
+
+Save this as `check.sh` and run before every story completion:
+
+```bash
+#!/bin/bash
+set -e
+
+echo "=== Checking Rust Backend ==="
+cd src-tauri
+cargo clippy --all-targets --all-features
+cargo check
+cargo test
+cd ..
+
+echo ""
+echo "=== Checking TypeScript Frontend ==="
+npx tsc --noEmit
+npx @biomejs/biome check src/
+npm run build
+
+echo ""
+echo "✅ ALL CHECKS PASSED!"
+```
+
+## Zero Tolerance Policy
+
+- **No exceptions:** All errors and warnings MUST be fixed
+- **No workarounds:** Don't disable rules unless absolutely necessary
+- **No "will fix later":** Fix immediately before story completion
+- **User must see clean output:** When running checks, show clean results to user
+
+## When Rules Conflict with Requirements
+
+If a linting rule conflicts with a legitimate requirement:
+
+1. Document why the rule must be bypassed
+2. Use the minimal scope for the exception (line/function, not file)
+3. Add a comment explaining the exception
+4. Get user approval
+
+Example:
+```typescript
+// Biome requires proper types, but react-markdown types are incompatible
+// Using unknown for compatibility
+const code = ({ className, children }: { className?: string; children?: React.ReactNode; [key: string]: unknown }) => {
+  ...
+}
+```
+
+## Integration with SDSW
+
+This checklist is part of **Step 4: Verification** in the Story-Driven Spec Workflow.
+
+**You cannot proceed to story acceptance without passing all checks.**