Fix facet pills replacing body instead of self on HTMX update

Add hx_target="this" to the dsl_facet_pills container to prevent HTMX
from inheriting hx_target="body" from the parent wrapper. Without this,
clicking a facet pill would cause the facet refresh to replace the entire
body with just the pills HTML, breaking forms on pages like /actions/outcome.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/animaltrack/web/templates/dsl_facets.py

@@ -71,6 +71,7 @@ def dsl_facet_pills(
         hx_get=htmx_url,
         hx_trigger=f"change from:#{filter_input_id} delay:600ms",
         hx_include=f"#{filter_input_id}",
+        hx_target="this",
         hx_swap="outerHTML",
         cls="space-y-3 mb-4",
     )

tests/e2e/test_facet_pills.py

@@ -122,6 +122,42 @@ class TestFacetPillsOnOutcomeForm:
         filter_input = page.locator("#filter")
         expect(filter_input).to_have_value("species:duck")
 
+    def test_facet_click_preserves_form_structure(self, page: Page, live_server):
+        """Clicking a facet pill should not replace the form with just pills.
+
+        Regression test: Without hx_target="this" on the facet pills container,
+        HTMX inherits hx_target="body" from the parent and replaces the entire
+        page body with just the facet pills HTML.
+        """
+        page.goto(f"{live_server.url}/actions/outcome")
+        expect(page.locator("body")).to_be_visible()
+
+        # Verify form elements are visible before clicking facet
+        outcome_select = page.locator("#outcome")
+        expect(outcome_select).to_be_visible()
+
+        filter_input = page.locator("#filter")
+        expect(filter_input).to_be_visible()
+
+        # Click a facet pill
+        duck_pill = page.locator('[data-facet-field="species"][data-facet-value="duck"]')
+        expect(duck_pill).to_be_visible()
+        duck_pill.click()
+
+        # Wait for HTMX to complete the facet refresh (600ms delay + network time)
+        # The facet pills use hx_trigger="change delay:600ms" so we must wait
+        page.wait_for_timeout(1000)
+        page.wait_for_load_state("networkidle")
+
+        # Form elements should still be visible after facet pills refresh
+        # If this fails, the body was replaced with just the facet pills
+        expect(outcome_select).to_be_visible()
+        expect(filter_input).to_be_visible()
+
+        # Verify the form can still be submitted (submit button visible)
+        submit_button = page.locator('button[type="submit"]')
+        expect(submit_button).to_be_visible()
+
 
 class TestFacetPillsOnTagAddForm:
     """Test facet pills functionality on the tag add form."""