feat(02-02): add driver upload endpoint with INF parsing and dedup

- POST /drivers/upload: validates ZIP, parses INF, persists via DriverStore + Peewee
- SHA256 dedup: get_or_create prevents duplicate Driver records
- GET /drivers route added to pages.py with driver_data context
- drivers.router registered in main.py
- drivers.html template with HTMX upload form
- partials/driver_list.html HTMX target with select dropdown and unused-file notice
- Fixed conftest client fixture to use context manager (triggers lifespan/init_db)
- [Rule 3] conftest: TestClient context manager required for lifespan trigger
- [Rule 1] drivers.py: dynamic DRIVERS_DIR read so monkeypatch works in tests

imptune/templates/drivers.html

@@ -0,0 +1,25 @@
+{% extends "base.html" %}
+{% block content %}
+<h1>Drivers</h1>
+
+<section>
+  <h2>Upload Driver Package</h2>
+  <form
+    hx-post="/drivers/upload"
+    hx-encoding="multipart/form-data"
+    hx-target="#driver-list"
+    hx-swap="outerHTML"
+    hx-indicator="#upload-spinner"
+  >
+    <label for="driver-file">Driver Package (ZIP containing .inf + driver files)</label>
+    <input type="file" id="driver-file" name="file" accept=".zip" required>
+    <button type="submit">Upload</button>
+    <span id="upload-spinner" class="htmx-indicator" aria-busy="true">Uploading...</span>
+  </form>
+</section>
+
+<section>
+  <h2>Driver Library</h2>
+  {% include "partials/driver_list.html" %}
+</section>
+{% endblock %}