docs: update all READMEs for v1.1.0

Add Electron desktop app section, document all 8 plugins, update
features list (assets, super-buckets, find/replace, arrow nav, PDF
upload), fix relay docs (chat shipped, not future), add missing API
endpoints, correct electron data storage paths and php-bin fetch info.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

electron/php-bin/README.md

@@ -6,17 +6,17 @@ installation.
 
 ## Download
 
-Get static builds from https://github.com/crazywhalecc/static-php-cli/releases
-(look for `php-8.3-*-cli` assets). Required extensions: pdo_sqlite, zip, session.
+Get static builds from https://dl.static-php.dev/static-php-cli/common/
+(look for `php-8.3.*-cli-*` files). Required extensions: pdo_sqlite, zip, session.
 
     linux/php       — x86_64 Linux ELF binary
-    darwin/php      — macOS universal binary (arm64 + x86_64)
-    win32/php.exe   — Windows PE binary
+    darwin/php      — macOS aarch64 binary
+    win32/php.exe   — Windows PE binary (not available from static-php-cli; use windows.php.net)
 
-## Quick fetch (Linux example)
+## Quick fetch
 
-    curl -L -o linux/php \
-      "https://dl.static-php.dev/static-php-cli/common/php-8.3.23-cli-linux-x86_64.tar.gz" \
-      && tar -xzf linux/php -C linux/ && rm linux/php.tar.gz
+Use the included script from the `electron/` directory:
 
-Make sure the binary is executable: `chmod +x linux/php`
+    ./fetch-php.sh
+
+This auto-detects the latest PHP 8.3 version and downloads Linux + macOS binaries.