feat: smart video size warnings + Jinja2 template autocomplete

Video size warnings:
- Add file_size field to ImmichAssetInfo from exifInfo.fileSizeInByte
- Expose per-target max_video_size (50 MB for Telegram, none for others)
- Compute has_oversized_videos and per-asset oversized flag in template context
- Default templates show warning only when videos actually exceed the limit
- Templates no longer hardcode Telegram-specific logic

Template autocomplete:
- New jinja-autocomplete.ts engine with contextual completions
- Top-level variables ({{ }}), asset/album fields (dot access in loops),
  Jinja2 filters (|), block tags ({% %}), and loop.* special vars
- JinjaEditor accepts optional variables prop via CodeMirror Compartment
- Wired into template-configs and command-template-configs pages

Also: fix template emoji (📷 → 📎) and sync sample_context with new vars.

frontend/src/lib/components/JinjaEditor.svelte

@@ -1,19 +1,24 @@
 <script lang="ts">
 	import { onMount } from 'svelte';
-	import { EditorView, Decoration, placeholder as cmPlaceholder, type DecorationSet } from '@codemirror/view';
-	import { EditorState, StateField, StateEffect } from '@codemirror/state';
+	import { EditorView, Decoration, keymap, placeholder as cmPlaceholder, type DecorationSet } from '@codemirror/view';
+	import { EditorState, StateField, StateEffect, Compartment } from '@codemirror/state';
 	import { StreamLanguage } from '@codemirror/language';
 	import { oneDark } from '@codemirror/theme-one-dark';
+	import { acceptCompletion } from '@codemirror/autocomplete';
 	import { getTheme } from '$lib/theme.svelte';
+	import { jinjaAutocomplete, type SlotVariables } from '$lib/editor/jinja-autocomplete';
 
-	let { value = '', onchange, rows = 6, placeholder = '', errorLine = null } = $props<{
+	let { value = '', onchange, rows = 6, placeholder = '', errorLine = null, variables = undefined } = $props<{
 		value: string;
 		onchange: (val: string) => void;
 		rows?: number;
 		placeholder?: string;
 		errorLine?: number | null;
+		variables?: SlotVariables;
 	}>();
 
+	const autocompleteCompartment = new Compartment();
+
 	let container: HTMLDivElement;
 	let view: EditorView;
 	const theme = getTheme();
@@ -71,6 +76,8 @@
 		const extensions = [
 			jinjaLang,
 			errorLineField,
+			autocompleteCompartment.of(variables ? jinjaAutocomplete(variables) : []),
+			keymap.of([{ key: 'Tab', run: acceptCompletion }]),
 			EditorView.updateListener.of((update) => {
 				if (update.docChanged) {
 					onchange(update.state.doc.toString());
@@ -86,6 +93,11 @@
 				'.ͼc': { color: '#e879f9' },
 				'.ͼd': { color: '#38bdf8' },
 				'.ͼ5': { color: '#6b7280' },
+				'.cm-tooltip-autocomplete': {
+					border: '1px solid var(--color-border)',
+					borderRadius: '0.375rem',
+					fontSize: '12px',
+				},
 			}),
 		];
 		if (isDark) extensions.push(oneDark);
@@ -116,6 +128,17 @@
 		}
 	});
 
+	// Update autocomplete when variables change
+	$effect(() => {
+		if (view) {
+			view.dispatch({
+				effects: autocompleteCompartment.reconfigure(
+					variables ? jinjaAutocomplete(variables) : [],
+				),
+			});
+		}
+	});
+
 	// Recreate editor when theme changes
 	let lastIsDark: boolean | undefined;
 	$effect(() => {