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/web.py

@@ -7,9 +7,10 @@ Serves a single live profile page built from the BigMind DB.
 import os
 import threading
 import logging
+from pathlib import Path
 from datetime import datetime, timezone, timedelta
 
-from bigmind.web_render import _render_html  # all HTML rendering lives there
+from bigmind.web_render import _render_html, _render_gallery_html  # all HTML rendering lives there
 
 logger = logging.getLogger("BigMindWeb")
 
@@ -17,13 +18,27 @@ _PORT = int(os.environ.get("BIGMIND_PORT", "7700"))
 _AUTOOPEN = os.environ.get("BIGMIND_AUTOOPEN", "").lower() in ("1", "true", "yes")
 _server_started = False
 
+# Gallery directory — images served from here
+_GALLERY_DIR = Path(os.environ.get("BIGMIND_GALLERY_DIR", Path.home() / ".mcp" / "bigmind" / "gallery"))
+
+# Profile image — last entry in gallery dir wins; fallback to original lumen-profile.png
+def _get_profile_image_path() -> Path | None:
+    """Return the path of the current profile image, or None if not found."""
+    # 1. Check gallery dir for lumen_profile* images (seed 568659042 = lumen_profile)
+    if _GALLERY_DIR.exists():
+        candidates = sorted(_GALLERY_DIR.glob("*.png"), reverse=True)
+        if candidates:
+            return candidates[0]  # most recently named = most recent timestamp
+    return None
+
 
 # ── Flask app ─────────────────────────────────────────────────────────────────
 
 def _create_app():
-    from flask import Flask, jsonify, request
+    from flask import Flask, jsonify, request, send_file, abort
     from bigmind import memory_store
     from bigmind.profile_builder import build_profile_data
+    from bigmind.db import db as _db
 
     app = Flask(__name__)
     app.logger.setLevel(logging.WARNING)  # silence Flask request logs
@@ -34,6 +49,39 @@ def _create_app():
         data = build_profile_data(user["id"])
         return _render_html(data)
 
+    @app.route("/profile-image")
+    def profile_image():
+        """Serve the current Lumen profile picture."""
+        img_path = _get_profile_image_path()
+        if img_path and img_path.exists():
+            return send_file(str(img_path), mimetype="image/png")
+        abort(404)
+
+    @app.route("/gallery/image/<filename>")
+    def gallery_image(filename: str):
+        """Serve a specific gallery image by filename."""
+        # Security: only allow alphanumeric + underscores + dots, no path traversal
+        safe_name = Path(filename).name
+        img_path = _GALLERY_DIR / safe_name
+        if img_path.exists() and img_path.suffix.lower() in (".png", ".jpg", ".jpeg", ".webp"):
+            mimetype = "image/png" if img_path.suffix.lower() == ".png" else "image/jpeg"
+            return send_file(str(img_path), mimetype=mimetype)
+        abort(404)
+
+    @app.route("/gallery")
+    def gallery():
+        """Render the AI-generated image gallery page."""
+        _GALLERY_DIR.mkdir(parents=True, exist_ok=True)
+        with _db() as conn:
+            rows = conn.execute(
+                """SELECT id, filename, prompt, tags, model, created_at,
+                          width, height, file_size_bytes
+                   FROM gallery_images
+                   ORDER BY created_at DESC"""
+            ).fetchall()
+        images = [dict(r) for r in rows]
+        return _render_gallery_html(images)
+
     @app.route("/api/session/<session_id>")
     def api_session(session_id):
         """Return Tier-2 summary JSON for a given session id."""