ci: add flake8 lint workflow; fix unused imports

Adds .gitea/workflows/lint.yml running flake8 with .flake8 config.
Removes unused imports (flask.redirect, flask.url_for, time, typing.Tuple).
Config ignores E221/E305 (intentional column alignment and function spacing).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.flake8

@@ -0,0 +1,6 @@
+[flake8]
+max-line-length = 120
+# E221: multiple spaces before operator — intentional column alignment
+# E305: two blank lines after function — relaxed for module-level code
+extend-ignore = E221, E305
+exclude = __pycache__, .git

.gitea/workflows/lint.yml

@@ -0,0 +1,20 @@
+name: Lint
+
+on:
+  push:
+    branches: ["**"]
+  pull_request:
+    branches: ["**"]
+
+jobs:
+  python-lint:
+    name: Python (flake8)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install flake8
+        run: pip install flake8
+
+      - name: Run flake8
+        run: flake8 .

app.py

@@ -13,7 +13,7 @@ import time
 import uuid
 from functools import wraps
 
-from flask import Flask, jsonify, redirect, render_template, request, url_for
+from flask import Flask, jsonify, render_template, request
 
 import db
 import diagnose
@@ -42,6 +42,7 @@ def inject_config():
         }
     }
 
+
 # In-memory diagnostic job store { job_id: { status, result, created_at } }
 _diag_jobs: dict = {}
 _diag_lock = threading.Lock()

diagnose.py

@@ -6,9 +6,8 @@ Executed in a background thread; results stored in _diag_jobs (app.py).
 """
 import re
 import shlex
-import time
 import logging
-from typing import Dict, List, Optional, Tuple
+from typing import Dict, List, Optional
 
 logger = logging.getLogger('gandalf.diagnose')