Remove recordings feature, replay sessions directly, bump to 0.6.0

Recordings were just a thin named pointer over an already-captured
session's events, so the whole separate feature (recordings table, API
routes, pages, UI) is gone: any completed session can now be named and
replayed directly. Replaying no longer creates a session or duplicates
events of its own - it just bumps the source session's playCount/lastPlayedAt.

Also renames play_sessions/playSession(s) to sessions/session(s) throughout
the schema, queries, API routes, and UI for consistency, and updates the
README to match the new flow.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

drizzle/0001_drop_recordings.sql

@@ -0,0 +1,17 @@
+DROP TABLE `recordings`;--> statement-breakpoint
+PRAGMA foreign_keys=OFF;--> statement-breakpoint
+CREATE TABLE `__new_play_sessions` (
+	`id` integer PRIMARY KEY AUTOINCREMENT NOT NULL,
+	`name` text,
+	`kind` text NOT NULL,
+	`status` text DEFAULT 'active' NOT NULL,
+	`started_at` integer NOT NULL,
+	`ended_at` integer,
+	`duration_ms` integer,
+	`notes` text
+);
+--> statement-breakpoint
+INSERT INTO `__new_play_sessions`("id", "name", "kind", "status", "started_at", "ended_at", "duration_ms", "notes") SELECT "id", "name", "kind", "status", "started_at", "ended_at", "duration_ms", "notes" FROM `play_sessions`;--> statement-breakpoint
+DROP TABLE `play_sessions`;--> statement-breakpoint
+ALTER TABLE `__new_play_sessions` RENAME TO `play_sessions`;--> statement-breakpoint
+PRAGMA foreign_keys=ON;