feat: smart git URL parsing for browser URLs

- Add git URL parsing utilities (extract_base_repo_url, parse_git_url)
- Support GitHub, GitLab, Bitbucket browser URL detection
- Add /projects/repositories/parse-url endpoint
- Enhance repository creation to detect browser URLs and suggest corrections
- Add real-time URL validation in frontend with debouncing
- Show visual indicators (green/yellow/red) for URL validity
- Display inline suggestions with 'Use Suggested' button
- Add comprehensive unit tests for URL parsing
- Quality gates: ruff ✓, mypy ✓, typecheck ✓, lint ✓, build ✓

openspec/changes/smart-git-url-parsing/specs/spec.md

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+# Smart Git URL Parsing Specification
+
+## Requirements
+
+### Functional Requirements
+
+1. **URL Detection**: Detect when a provided URL is a browser URL rather than a git clone URL
+2. **URL Extraction**: Extract the base repository URL from browser URLs
+3. **User Confirmation**: Show extracted URL to user and ask for confirmation
+4. **Flexible Input**: Allow users to proceed with original URL if they prefer
+5. **Multiple Hosts**: Support GitHub, GitLab, Bitbucket, and generic git hosts
+
+### Non-Functional Requirements
+
+1. **Performance**: URL parsing should be instant (< 100ms)
+2. **Accuracy**: Should correctly identify 95%+ of browser URLs
+3. **User Experience**: Clear, helpful messages without technical jargon
+4. **Backward Compatibility**: Existing valid git URLs should continue to work
+
+## API Specification
+
+### POST /git-repositories/parse-url
+Parse a URL and determine if it's a valid clone URL or needs correction.
+
+**Request Body:**
+```json
+{
+  "url": "https://github.com/user/repo/tree/main"
+}
+```
+
+**Response 200:**
+```json
+{
+  "original_url": "https://github.com/user/repo/tree/main",
+  "base_url": "https://github.com/user/repo.git",
+  "is_valid_clone_url": false,
+  "needs_parsing": true,
+  "host": "github.com",
+  "message": "This URL contains a branch path. The repository URL is: https://github.com/user/repo.git"
+}
+```
+
+**Response 200 (already valid):**
+```json
+{
+  "original_url": "https://github.com/user/repo.git",
+  "base_url": "https://github.com/user/repo.git",
+  "is_valid_clone_url": true,
+  "needs_parsing": false,
+  "host": "github.com",
+  "message": "Valid git repository URL"
+}
+```
+
+### Enhanced POST /projects/{project_id}/repositories
+Enhanced to return suggestions when URL needs parsing.
+
+**New 422 Response:**
+```json
+{
+  "detail": "The provided URL appears to be a browser URL, not a git clone URL",
+  "suggested_url": "https://github.com/user/repo.git",
+  "original_url": "https://github.com/user/repo/tree/main",
+  "error_code": "URL_NEEDS_PARSING"
+}
+```
+
+**Request Body (with force flag):**
+```json
+{
+  "name": "my-repo",
+  "remote_url": "https://github.com/user/repo/tree/main",
+  "is_mirror": false,
+  "force_original_url": true
+}
+```
+
+## Data Model
+
+### URLParseResult
+```python
+class URLParseResult:
+    original_url: str
+    base_url: str | None
+    is_valid_clone_url: bool
+    needs_parsing: bool
+    host: str | None
+    message: str
+    error_code: str | None
+```
+
+## URL Parsing Rules
+
+### Supported Hosts
+- github.com
+- gitlab.com  
+- bitbucket.org
+- Any custom domain with git hosting
+
+### GitHub URL Patterns
+```
+https://github.com/{owner}/{repo} → valid
+https://github.com/{owner}/{repo}.git → valid
+https://github.com/{owner}/{repo}/tree/{branch} → extract base
+https://github.com/{owner}/{repo}/blob/{branch}/{path} → extract base
+https://github.com/{owner}/{repo}/pull/{number} → extract base
+https://github.com/{owner}/{repo}/issues/{number} → extract base
+https://github.com/{owner}/{repo}/actions → extract base
+```
+
+### GitLab URL Patterns
+```
+https://gitlab.com/{owner}/{repo} → valid
+https://gitlab.com/{owner}/{repo}.git → valid
+https://gitlab.com/{owner}/{repo}/-/tree/{branch} → extract base
+https://gitlab.com/{owner}/{repo}/-/blob/{branch}/{path} → extract base
+https://gitlab.com/{owner}/{repo}/-/merge_requests/{number} → extract base
+```
+
+### Bitbucket URL Patterns
+```
+https://bitbucket.org/{owner}/{repo} → valid
+https://bitbucket.org/{owner}/{repo}.git → valid
+https://bitbucket.org/{owner}/{repo}/src/{branch} → extract base
+```
+
+### Extraction Algorithm
+1. Parse URL components (scheme, netloc, path, query)
+2. Remove query parameters entirely
+3. Split path by `/`
+4. Remove trailing segments that indicate non-repo paths:
+   - `tree/*`, `blob/*`, `pull/*`, `issues/*`, `actions`
+   - `-/tree/*`, `-/blob/*`, `-/merge_requests/*`
+   - `src/*`
+5. Reconstruct URL with remaining path
+6. Add `.git` suffix if missing (for HTTPS URLs)
+7. Return extracted URL
+
+## Frontend Specification
+
+### URL Input Component
+- Input field for repository URL
+- Real-time validation (debounced 300ms)
+- Visual indicators:
+  - 🟢 Green border: Valid git URL
+  - 🟡 Yellow border: Browser URL detected, suggestion shown
+  - 🔴 Red border: Invalid/malformed URL
+- Inline suggestion banner below input:
+  ```
+  ⚠️ This looks like a browser URL
+  Suggested: https://github.com/user/repo.git
+  [Use Suggested] [Keep Original]
+  ```
+
+### Confirmation Dialog
+Shown when backend returns 422 with suggestion:
+```
+┌─────────────────────────────────────┐
+│ URL Correction Suggestion            │
+├─────────────────────────────────────┤
+│                                      │
+│ The URL you entered appears to be   │
+│ a browser URL, not a git clone URL. │
+│                                      │
+│ Original:                            │
+│ https://github.com/user/repo/tree/main│
+│                                      │
+│ Suggested repository URL:            │
+│ https://github.com/user/repo.git     │
+│                                      │
+│ [Use Suggested URL]  [Use Original] │
+│ [Cancel]                            │
+└─────────────────────────────────────┘
+```
+
+## Error Codes
+
+| Error Code | Description | User Message |
+|------------|-------------|--------------|
+| URL_NEEDS_PARSING | Browser URL detected | "This looks like a browser URL. Did you mean: {suggested_url}?" |
+| INVALID_URL | Malformed URL | "Please enter a valid URL" |
+| UNSUPPORTED_HOST | Unknown git host | "This git host is not supported" |
+| CLONE_FAILED | Git clone failed | "Failed to clone repository: {error}" |
+| AUTH_REQUIRED | Private repo, need auth | "This repository requires authentication" |
+
+## Testing Strategy
+
+### Unit Tests (URL Parsing)
+- Test all GitHub URL patterns
+- Test all GitLab URL patterns  
+- Test all Bitbucket URL patterns
+- Test valid URLs pass through unchanged
+- Test edge cases (subgroups, nested paths, etc.)
+
+### Integration Tests
+- Test parse-url endpoint with various URLs
+- Test repository creation with browser URL (should suggest correction)
+- Test repository creation with force flag
+- Test clone operation with corrected URL
+
+### Frontend Tests
+- Test URL input validation states
+- Test suggestion banner display
+- Test confirmation dialog flow
+- Test acceptance/rejection of suggestions