feat: locks/replace/compare/permalinks; perf: virtualization, LQIP, caching, diagnostics; add tests, docs, and issue/PR templates (flags OFF)

DOCKER.md

@@ -34,6 +34,36 @@ Then open http://localhost:8080
 
 Volumes are the same as the CLI service, so deck exports/logs/configs persist in your working folder.
 The app serves a favicon at `/favicon.ico` and exposes a health endpoint at `/healthz`.
+Compare view offers a Copy summary button to copy a plain-text diff of two runs.
+
+Web UI feature highlights:
+- Locks: Click a card or the lock control in Step 5; locks persist across reruns.
+- Replace: Enable Replace in Step 5, click a card to open Alternatives (filters include Owned-only), then choose a swap.
+- Permalinks: Copy a permalink from Step 5 or a Finished deck; paste via “Open Permalink…” to restore.
+- Compare: Use the Compare page from Finished Decks; quick actions include Latest two and Swap A/B.
+
+Virtualized lists and lazy images (opt‑in)
+- Set `WEB_VIRTUALIZE=1` to enable virtualization in Step 5 grids/lists and the Owned library for smoother scrolling on large sets.
+- Example (Compose):
+    ```yaml
+    services:
+        web:
+            environment:
+                - WEB_VIRTUALIZE=1
+    ```
+- Example (Docker Hub):
+    ```powershell
+    docker run --rm -p 8080:8080 `
+        -e WEB_VIRTUALIZE=1 `
+        -v "${PWD}/deck_files:/app/deck_files" `
+        -v "${PWD}/logs:/app/logs" `
+        -v "${PWD}/csv_files:/app/csv_files" `
+        -v "${PWD}/owned_cards:/app/owned_cards" `
+        -v "${PWD}/config:/app/config" `
+    -e SHOW_DIAGNOSTICS=1 ` # optional: enables diagnostics tools and overlay
+    mwisnowski/mtg-python-deckbuilder:latest `
+        bash -lc "cd /app && uvicorn code.web.app:app --host 0.0.0.0 --port 8080"
+    ```
 
 ### Diagnostics and logs (optional)
 Enable internal diagnostics and a read-only logs viewer with environment flags.
@@ -44,6 +74,7 @@ Enable internal diagnostics and a read-only logs viewer with environment flags.
 When enabled:
 - `/logs` supports an auto-refresh toggle with interval, a level filter (All/Error/Warning/Info/Debug), and a Copy button to copy the visible tail.
 - `/status/sys` returns a simple system summary (version, uptime, UTC server time, and feature flags) and is shown on the Diagnostics page when `SHOW_DIAGNOSTICS=1`.
+ - Virtualization overlay: press `v` on pages with virtualized grids to toggle per-grid overlays and a global summary bubble.
 
 Compose example (web service):
 ```yaml
@@ -125,6 +156,8 @@ GET http://localhost:8080/healthz  ->  { "status": "ok", "version": "dev", "upti
 ### Web UI tuning env vars
 - WEB_TAG_PARALLEL=1|0 (parallel tagging on/off)
 - WEB_TAG_WORKERS=<N> (process count; set based on CPU/memory)
+- WEB_VIRTUALIZE=1 (enable virtualization)
+- SHOW_DIAGNOSTICS=1 (enables diagnostics pages and overlay hotkey `v`)
 
 ## Manual build/run
 ```powershell