feat: custom progression mode — skip loading/testing phase

PRD #51 US1. Add ProgressionMode (liftcoach/custom) to mesocycle.
Custom mode: exercises start pending with blank sets, no Week 0.
Progression mode selection screen in planner flow.
Guard extendMicrocycle() for custom mode until carry-forward lands.

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

Author: tomkis

drizzle/0004_thick_mimic.sql

@@ -0,0 +1,19 @@
+PRAGMA foreign_keys=OFF;--> statement-breakpoint
+CREATE TABLE `__new_workout_exercise_set` (
+	`id` text PRIMARY KEY NOT NULL,
+	`workout_exercise_id` text NOT NULL,
+	`state` text NOT NULL,
+	`order_index` integer NOT NULL,
+	`reps` integer,
+	`weight` real,
+	`created_at` integer NOT NULL,
+	`updated_at` integer NOT NULL,
+	FOREIGN KEY (`workout_exercise_id`) REFERENCES `workout_exercise`(`id`) ON UPDATE no action ON DELETE no action
+);
+--> statement-breakpoint
+INSERT INTO `__new_workout_exercise_set`("id", "workout_exercise_id", "state", "order_index", "reps", "weight", "created_at", "updated_at") SELECT "id", "workout_exercise_id", "state", "order_index", "reps", "weight", "created_at", "updated_at" FROM `workout_exercise_set`;--> statement-breakpoint
+DROP TABLE `workout_exercise_set`;--> statement-breakpoint
+ALTER TABLE `__new_workout_exercise_set` RENAME TO `workout_exercise_set`;--> statement-breakpoint
+PRAGMA foreign_keys=ON;--> statement-breakpoint
+CREATE INDEX `workout_exercise_set_workout_exercise_id_idx` ON `workout_exercise_set` (`workout_exercise_id`);--> statement-breakpoint
+ALTER TABLE `mesocycle` ADD `progression_mode` text DEFAULT 'liftcoach' NOT NULL;