feat(bigmind): profile image + AI image gallery (schema v8)

- web.py: add /profile-image route (serves most-recent gallery PNG)
  add /gallery/image/<filename> route (per-image serving)
  add /gallery route (renders gallery page from DB)
  add _get_profile_image_path() helper
- web_render.py: replace emoji avatar with <img src=/profile-image>
  onerror fallback to 🧠 emoji
  add .nav bar with Profile/Gallery links to both pages
  add _render_gallery_html() full gallery page renderer
  add gallery CSS: .gal-grid, .gal-card, .gal-img, .gal-info, etc.
- db.py: bump SCHEMA_VERSION 7→8
  add gallery_images table (id, filename, prompt, tags, model,
    created_at, width, height, file_size_bytes)
  add _migrate_v7_to_v8() migration function
  add init_db() hook for v<8 migration
- tests: update test_schema_version_is_7→8 in test_db.py and
  test_feature7_live_sessions.py; add gallery_images to expected tables

Storage strategy: Option B (filesystem + DB metadata)
Images in ~/.mcp/bigmind/gallery/, metadata in SQLite
Pre-populated with 5 lumen_profiles images (seeds 2409122067,
764633840, 1367851518, 3135233944, 568659042)

Tests: 297/297 passing

mcp/bigmind/bigmind/db.py

@@ -14,7 +14,7 @@ from typing import Generator
 
 logger = logging.getLogger("BigMindDB")
 
-SCHEMA_VERSION = 7
+SCHEMA_VERSION = 8
 DEFAULT_DB_PATH = Path.home() / ".mcp" / "bigmind" / "memory.db"
 
 # ─── DDL ─────────────────────────────────────────────────────────────────────
@@ -222,6 +222,22 @@ _DDL_STATEMENTS = [
         notes,
         tokenize = 'porter unicode61'
     )""",
+
+    # ── GALLERY IMAGES — AI-generated image archive ──────────────────────────
+    """CREATE TABLE IF NOT EXISTS gallery_images (
+        id              INTEGER PRIMARY KEY AUTOINCREMENT,
+        filename        TEXT NOT NULL UNIQUE,
+        prompt          TEXT,
+        tags            TEXT,
+        model           TEXT,
+        created_at      DATETIME DEFAULT CURRENT_TIMESTAMP,
+        width           INTEGER,
+        height          INTEGER,
+        file_size_bytes INTEGER
+    )""",
+
+    """CREATE INDEX IF NOT EXISTS idx_gallery_created
+       ON gallery_images(created_at DESC)""",
 ]
 
 
@@ -407,6 +423,8 @@ def init_db() -> None:
             _migrate_v5_to_v6(conn)
         if current_version < 7:
             _migrate_v6_to_v7(conn)
+        if current_version < 8:
+            _migrate_v7_to_v8(conn)
 
         # Write / update the version
         if row:
@@ -457,6 +475,28 @@ def _migrate_v6_to_v7(conn: sqlite3.Connection) -> None:
     logger.info("BigMind schema migrated v6 → v7 (people/contacts directory)")
 
 
+def _migrate_v7_to_v8(conn: sqlite3.Connection) -> None:
+    """v7 → v8: add gallery_images table for AI-generated image archive."""
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS gallery_images (
+            id              INTEGER PRIMARY KEY AUTOINCREMENT,
+            filename        TEXT NOT NULL UNIQUE,
+            prompt          TEXT,
+            tags            TEXT,
+            model           TEXT,
+            created_at      DATETIME DEFAULT CURRENT_TIMESTAMP,
+            width           INTEGER,
+            height          INTEGER,
+            file_size_bytes INTEGER
+        )
+    """)
+    conn.execute("""
+        CREATE INDEX IF NOT EXISTS idx_gallery_created
+        ON gallery_images(created_at DESC)
+    """)
+    logger.info("BigMind schema migrated v7 → v8 (gallery_images table)")
+
+
 def vacuum_db() -> None:
     """Run VACUUM outside of any transaction (SQLite requirement)."""
     db_path = get_db_path()