feat(events): restore PDF→webp convert button in event file table

Adds a per-row "Convert PDF → Image" button in ae_comp__event_file_obj_tbl.
Only shown when edit_mode is on, the file is a PDF, and the session
type_code is 'poster' — poster sessions need images in the Launcher modal
(which uses <img>, not a PDF viewer).

Calls GET /v3/action/hosted_file/{id}/convert_file (pdf2image, 3840px wide,
first page, saves as a new hosted_file linked to the same parent object).
Per-row status tracking: idle → converting → done | error with retry.

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

src/routes/events/ae_comp__event_file_obj_tbl.svelte

@@ -65,6 +65,53 @@
     let horiz_scroll_warning: boolean = $state(false);
     let horiz_check_element: HTMLElement | null = $state(null);
 
+    // PDF → Image conversion state (keyed by event_file_id)
+    // WHY: Poster sessions display files in the Launcher modal via <img> tag — PDFs can't render there.
+    // Presenters upload PDFs which must be converted server-side to high-res webp images.
+    // Button is only shown in edit_mode for PDF files linked to a poster-type session.
+    // Backend: /v3/action/hosted_file/{id}/convert_file runs pdf2image (3840px wide, first page only)
+    // and saves the result as a new hosted_file record linked to the same parent object.
+    type ConvertStatus = 'idle' | 'converting' | 'done' | 'error';
+    let convert_status_kv: Record<string, ConvertStatus> = $state({});
+    let convert_result_kv: Record<string, any> = $state({});
+
+    async function handle_convert_pdf_to_image(event_file_obj: any) {
+        const file_id = event_file_obj.event_file_id;
+        convert_status_kv[file_id] = 'converting';
+        try {
+            // Link the new image to the most specific parent available
+            const link_to_type = event_file_obj.event_session_id ? 'event_session'
+                : event_file_obj.event_presentation_id ? 'event_presentation'
+                : 'event';
+            const link_to_id = event_file_obj.event_session_id
+                || event_file_obj.event_presentation_id
+                || event_file_obj.event_id;
+            const filename_no_ext = (event_file_obj.filename ?? 'poster_image').replace(/\.pdf$/i, '');
+            const url = `${$ae_api.base_url}/v3/action/hosted_file/${event_file_obj.hosted_file_id}/convert_file`
+                + `?link_to_type=${encodeURIComponent(link_to_type)}`
+                + `&link_to_id=${encodeURIComponent(link_to_id)}`
+                + `&filename_no_ext=${encodeURIComponent(filename_no_ext)}`
+                + `&to_type=webp`;
+            const resp = await fetch(url, {
+                headers: {
+                    'x-aether-api-key': $ae_api.api_secret_key,
+                    'x-account-id': String($ae_api.account_id ?? '')
+                }
+            });
+            const body = await resp.json();
+            if (resp.ok && body?.data) {
+                convert_result_kv[file_id] = body.data;
+                convert_status_kv[file_id] = 'done';
+            } else {
+                console.error('[convert_pdf] API error:', body);
+                convert_status_kv[file_id] = 'error';
+            }
+        } catch (err) {
+            console.error('[convert_pdf] Fetch failed:', err);
+            convert_status_kv[file_id] = 'error';
+        }
+    }
+
     // Check if element is scrolling horizontally
     $effect(() => {
         if (
@@ -437,7 +484,44 @@
                                     max_filename={50}
                                     classes="btn btn-sm preset-tonal-primary hover:preset-filled-primary-500 min-w-72"
                                 />
-                                <!-- {event_file_obj?.filename} -->
+                                <!-- PDF → webp convert button: only for poster sessions in edit mode -->
+                                {#if $ae_loc.edit_mode && event_file_obj?.extension === 'pdf' && event_file_obj?.event_session_type_code === 'poster'}
+                                    <div class="mt-1">
+                                        {#if !convert_status_kv[event_file_obj.event_file_id] || convert_status_kv[event_file_obj.event_file_id] === 'idle'}
+                                            <button
+                                                type="button"
+                                                class="btn btn-sm preset-tonal-warning border border-warning-500"
+                                                title="Convert this PDF to a high-res webp image for use in the Launcher poster display."
+                                                onclick={() => handle_convert_pdf_to_image(event_file_obj)}
+                                            >
+                                                <span class="fas fa-file-image mx-1"></span>
+                                                Convert PDF → Image
+                                            </button>
+                                        {:else if convert_status_kv[event_file_obj.event_file_id] === 'converting'}
+                                            <span class="btn btn-sm preset-tonal-surface opacity-60 cursor-wait">
+                                                <span class="fas fa-spinner fa-spin mx-1"></span>
+                                                Converting…
+                                            </span>
+                                        {:else if convert_status_kv[event_file_obj.event_file_id] === 'done'}
+                                            <span class="btn btn-sm preset-tonal-success" title="Conversion complete. New webp hosted_file created: {convert_result_kv[event_file_obj.event_file_id]?.filename ?? ''}">
+                                                <span class="fas fa-check mx-1"></span>
+                                                Done — {convert_result_kv[event_file_obj.event_file_id]?.filename ?? 'image created'}
+                                            </span>
+                                        {:else if convert_status_kv[event_file_obj.event_file_id] === 'error'}
+                                            <button
+                                                type="button"
+                                                class="btn btn-sm preset-tonal-error border border-error-500"
+                                                title="Conversion failed. Click to retry."
+                                                onclick={() => {
+                                                    convert_status_kv[event_file_obj.event_file_id] = 'idle';
+                                                }}
+                                            >
+                                                <span class="fas fa-exclamation-triangle mx-1"></span>
+                                                Failed — Retry?
+                                            </button>
+                                        {/if}
+                                    </div>
+                                {/if}
                             </td>
                             <td
                                 class="px-4 py-2 flex flex-col gap-0.5"