Seed the vendor catalogue into SQL and add an optional AI course advisor

Course metadata: a scan now gives every course a course_meta row from the
downloader's sidecar JSON when the folder has one, else from catalog_courses
matched by the folder name the downloader would create (folderKeyFor, a port
of ine.py's sanitize_name). tools/build-catalog-seed.php turns the INE export
into seeds/ine_catalog.sql, an idempotent patch that creates its own table and
upserts by id, so it can be applied to the live server before or after the
code and re-run freely. Course pages show the blurb, difficulty, vendor and
tags; search matches tags and blurbs; Settings reports how each course got its
details. Against the live library 163 of 179 courses match.

Course advisor, off by default: api/advisor.php answers "which course should I
take to learn X / what comes before Y" with courses from the library, in
order, plus vendor courses not yet downloaded. includes/ai_client.php is a
small curl wrapper for any OpenAI-format chat endpoint (DeepSeek V4 Flash by
default, no composer); the prompt is a byte-stable catalogue of the library so
the provider's prefix cache covers it. Every course id the model returns is
validated server-side, a bad JSON reply gets one retry then a plain-text
fallback, and a per-user daily cap with token counts lives in
advisor_requests. With AI_ENABLED false the app makes no outbound requests
and the box does not appear; users can also hide it per browser.

Claude-Session: https://claude.ai/code/session_012enquL2RZdjy3D5AcKP5yx

schema.sql

@@ -96,6 +96,66 @@ CREATE TABLE IF NOT EXISTS quizzes (
     INDEX idx_quizzes_folder (folder_id)
 ) ENGINE=InnoDB;
 
+-- The vendor's course catalogue (an INE export), applied by seeds/ine_catalog.sql
+-- (built with tools/build-catalog-seed.php) — never written by a scan.
+-- `folder_key` is the folder name the downloader creates for a course (see
+-- folderKeyFor() in includes/functions.php), which is how a library folder is
+-- matched to its catalogue entry.
+CREATE TABLE IF NOT EXISTS catalog_courses (
+    id                VARCHAR(64) PRIMARY KEY,        -- vendor uuid
+    name              VARCHAR(255) NOT NULL,
+    slug              VARCHAR(255) NOT NULL,
+    folder_key        VARCHAR(255) NOT NULL,
+    vendor            VARCHAR(100) NULL,
+    difficulty        VARCHAR(32)  NULL,
+    tags              TEXT NULL,                      -- JSON array of strings
+    short_description TEXT NULL,
+    description       TEXT NULL,
+    learning_paths    TEXT NULL,                      -- JSON array of names
+    categories        TEXT NULL,                      -- JSON array of names
+    duration_seconds  INT UNSIGNED NULL,
+    url               VARCHAR(500) NULL,
+    updated_at        TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+        ON UPDATE CURRENT_TIMESTAMP,
+    INDEX idx_cc_folder_key (folder_key)
+) ENGINE=InnoDB;
+
+-- What is known about one library course beyond its folder name: taken from
+-- the sidecar JSON the downloader leaves in a fully downloaded course, else
+-- from catalog_courses by folder name. Rewritten by every scan.
+CREATE TABLE IF NOT EXISTS course_meta (
+    folder_id         INT UNSIGNED PRIMARY KEY,
+    source            ENUM('sidecar', 'catalog') NOT NULL,
+    catalog_id        VARCHAR(64) NULL,
+    title             VARCHAR(255) NULL,
+    vendor            VARCHAR(100) NULL,
+    difficulty        VARCHAR(32)  NULL,
+    tags              TEXT NULL,
+    short_description TEXT NULL,
+    description       TEXT NULL,
+    learning_paths    TEXT NULL,
+    categories        TEXT NULL,
+    duration_seconds  INT UNSIGNED NULL,
+    updated_at        TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+        ON UPDATE CURRENT_TIMESTAMP,
+    CONSTRAINT fk_cm_folder FOREIGN KEY (folder_id) REFERENCES folders(id) ON DELETE CASCADE
+) ENGINE=InnoDB;
+
+-- One row per question put to the AI course advisor: the per-user daily cap
+-- and a record of what it cost. Created lazily on first use, like login_attempts.
+CREATE TABLE IF NOT EXISTS advisor_requests (
+    id                INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+    user_id           INT UNSIGNED NOT NULL,
+    created_at        TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    ok                TINYINT(1) NOT NULL DEFAULT 0,
+    model             VARCHAR(64) NULL,
+    prompt_tokens     INT UNSIGNED NULL,
+    cache_hit_tokens  INT UNSIGNED NULL,
+    completion_tokens INT UNSIGNED NULL,
+    INDEX idx_ar_user_time (user_id, created_at),
+    CONSTRAINT fk_ar_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+) ENGINE=InnoDB;
+
 -- Per-user quiz results. completed = every question answered correctly
 -- in a single attempt (sticky).
 CREATE TABLE IF NOT EXISTS quiz_progress (