Refresh README with recent features

Add YouTube video integration, reflexive-verb list + practice-pool
filters, verb-detail example sentences, lyrics word lookup. Bump iOS /
Xcode requirements to 26. Correct grammar-note count and document the
YouTubeKit + AVFoundation muxing architecture plus the video-curation
script.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -9,15 +9,18 @@ A Spanish-learning iOS app that combines verb conjugation practice, a full textb
 - **Focus modes** — weak verbs (SM-2 spaced repetition), irregularity drills (spelling / stem / unique), common tenses
 - **1,750 verbs** across 5 levels (Basic → Expert) with 209 K pre-conjugated forms and 23 K irregular-span annotations
 - **20 tenses** — every indicative, subjunctive, conditional, and imperative tense, each with character-level irregular highlighting
-- **Irregularity filter** — search the verb list by Any Irregular / Spelling Change / Stem Change / Unique Irregular, combinable with level filter
+- **Verb list filters** — search by level, by irregularity (Any / Spelling Change / Stem Change / Unique Irregular), or by reflexive only (curated 100-verb list); filters compose
+- **Practice pool filters** (Settings) — multi-select per level, per tense, per irregular-type, plus a "reflexive verbs only" toggle. Practice pool = intersection of all four.
+- **Verb detail pages** — conjugation table, six AI-generated example sentences (one per core tense), and reflexive infinitive + preposition hint for curated reflexive verbs
 - **Text-to-speech** on any form
 
 ### Content & study
 - **Textbook reader** — 30 chapters of *Complete Spanish Step-by-Step* with 251 interactive exercises (keyboard + Apple Pencil), 931 OCR'd vocab tables rendered as Spanish→English grids (~3 100 paired cards extracted via bounding-box OCR)
 - **Course decks** — weekly vocab decks with example sentences, week tests, and cumulative checkpoint exams
 - **Stem-change toggle** on Week 4 flashcard decks (E-IE, E-I, O-UE, U-UE) showing inline present-tense conjugations
-- **Grammar guide** — 20 tense guides with usage rules and examples + 20+ grammar topic notes (ser/estar, por/para, preterite/imperfect, etc.), each with 100+ practice exercises
+- **Grammar guide** — 20 tense guides with usage rules and examples + 36 grammar topic notes (ser/estar, por/para, preterite/imperfect, reflexives, subjunctive triggers, etc.), each with 100+ practice exercises
 - **Grammar exercises** — interactive quizzes for 5 core topics (ser/estar, por/para, preterite/imperfect, subjunctive, personal *a*)
+- **Curated YouTube videos** — 54 hand-picked videos attached to guide and grammar items (preference for The Language Tutor's numbered lessons + BaseLang). Each item offers three actions: **Stream** (opens YouTube app / Safari), **Download** (YouTubeKit extraction + AVFoundation mux for modern adaptive-stream videos), **Play** (full-screen AVPlayer from local MP4). Settings → Downloaded Videos lists all downloads with total size, per-item delete, and a 500 MB warning.
 
 ### AI & speech
 - **Conversational practice** — on-device AI chat partner (Apple Foundation Models) with 10 scenario types; chat bubbles have tappable words that open dictionary / on-demand AI lookup
@@ -29,7 +32,7 @@ A Spanish-learning iOS app that combines verb conjugation practice, a full textb
 - **Offline dictionary** — reverse index of 175 K verb forms + 200 common words, cached to disk for instant lookups
 - **Vocab SRS review** — spaced repetition over course vocabulary with Again / Hard / Good / Easy rating
 - **Cloze practice** — fill-in-the-blank sentences with distractor generation
-- **Lyrics practice** — search, translate, and read Spanish song lyrics
+- **Lyrics practice** — search, translate, and read Spanish song lyrics; long-press any word for an instant definition + tense/person readout (for verbs)
 
 ### Tracking & sync
 - **Progress** — streaks, daily goals, accuracy stats, achievement badges, study-time tracking per day
@@ -39,18 +42,21 @@ A Spanish-learning iOS app that combines verb conjugation practice, a full textb
 ## Architecture
 
 - **SwiftUI** + **SwiftData** with a dual-store configuration:
-  - **Local store** (App Group `group.com.conjuga.app`) — reference data: verbs, forms, irregular spans, tense guides, course decks, vocab cards, textbook chapters. Seeded from bundled JSON on first launch. Self-healing re-seeds trigger on version bumps *or* if rows are missing on disk.
+  - **Local store** (App Group `group.com.conjuga.app`) — reference data + per-device artifacts: verbs, forms, irregular spans, tense guides, course decks, vocab cards, textbook chapters, and downloaded videos. Seeded from bundled JSON on first launch. Self-healing re-seeds trigger on version bumps *or* if rows are missing on disk.
   - **Cloud store** (CloudKit `iCloud.com.conjuga.app`, private database) — user data: review cards, course reviews, user progress, test results, daily logs, saved songs, stories, conversations, textbook exercise attempts.
 - **SharedModels** Swift Package shared between the app and widget extension. Widget schema must include every local-store entity or SwiftData destructively migrates the shared store.
-- **Foundation Models** for on-device AI generation (`@Generable` structs for typed output).
+- **Foundation Models** for on-device AI generation (`@Generable` structs for typed output) — conversation partner, short stories, verb-detail example sentences.
 - **Vision** framework for OCR of textbook pages and vocabulary images.
 - **Speech** framework for recognition and pronunciation scoring.
+- **YouTubeKit** (SPM) for video stream URL extraction, paired with **AVFoundation** (`AVMutableComposition` + `AVAssetExportSession` passthrough) to mux separate DASH video + audio tracks into a single MP4 when progressive streams aren't available.
 - **Textbook extraction pipeline** (`Conjuga/Scripts/textbook/`) — XHTML and answer-key parsers, macOS Vision image OCR + PDF page OCR, bounding-box vocab pair extractor, NSSpellChecker-based validator, and language-aware auto-fixer.
+- **Video curation tooling** (`Conjuga/Scripts/generate_videos_markdown.py`) — regenerates `Conjuga/youtube_videos.md` with per-video channel, upload date, duration, view count, and like count (pulled via yt-dlp).
 
 ## Requirements
 
-- iOS 18+ (iOS 26 for Foundation Models features)
+- iOS 26+ (Foundation Models, Liquid Glass, modern Swift concurrency)
-- Xcode 16+
+- Xcode 26+
+- Apple Intelligence-capable device for AI features (conversation partner, AI stories, verb-detail examples); other features degrade gracefully
 
 ## Building