Add pluggable movement strategies (v1.3.0)

Turn the hardcoded straight-line sweep into a strategy system behind three
seams so new patterns are easy to add and, for the first time, testable
without nut.js or a real screen:

- src/device.ts:     injectable Device seam over nut.js (autoDelayMs lives
                     here now); the only module that touches the native lib.
- src/strategies.ts: pure per-pattern path generators + registry + lenient
                     name resolution. Ships line, diagonal, jitter, walk,
                     arc, figureEight.
- src/executor.ts:   single executePath driver owning bounds policy
                     (abort/clamp/reflect), pacing, interrupt detection, and
                     restore-on-clean.

keeper.ts's simulateActivity now selects a strategy and delegates to the
executor; the default `line` pattern is byte-for-byte the previous behavior.

New config surface, layered CLI > file > default with strict validation:
- -p/--pattern <name>   movement strategy (names matched case/-/_-insensitive)
- -s/--step-size <px>   pixels per step; stepCount is now a step *count*

Robustness for the new edge-seeking patterns: interrupt detection compares
against the last commanded (rounded) point with a 2px tolerance, and
clamp/reflect stay a couple pixels off the screen edge, so sub-pixel cursor
placement on scaled/multi-monitor displays isn't misread as user activity.
jitter's radius scales with sweep length so it moves at the default stepSize.

Tests: new suites for strategies, the executor (all bounds policies,
rounding, interrupt, tolerance, pacing), and the keeper loop; config and
configFile suites extended for pattern/stepSize. editor.test.ts moved to
tests/ for consistency. 64 pass.

src/config.ts

@@ -22,6 +22,7 @@
 import { join } from "node:path";
 
 import { CliError } from "./errors.ts";
+import { isPatternName, type PatternName } from "./strategies.ts";
 
 // Single source of truth for default values. The same file ships in the
 // install tree and is copied to $XDG_CONFIG_HOME/move/config.json on a
@@ -41,7 +42,12 @@ import seedRaw from "../scripts/config.default.json" with { type: "json" };
  * - `stepDelay`     — pause between individual synthetic mouse steps inside
  *                     a sweep. Also the window in which the user can
  *                     "interrupt" by moving the cursor. Milliseconds.
- * - `stepCount`     — number of pixel-steps in a single sweep. Pixels.
+ * - `stepCount`     — number of steps in a single sweep. Count.
+ * - `stepSize`      — pixels moved per step. Decouples "how many steps"
+ *                     from "how far each step travels" so non-linear
+ *                     patterns can span meaningful distances. Pixels.
+ * - `pattern`       — name of the movement strategy to use (see
+ *                     `strategies.ts`; e.g. `line`, `walk`, `arc`).
  * - `verbose`       — whether per-sweep / interrupt / bounds events are
  *                     logged. The startup banner is always printed.
  */
@@ -50,6 +56,8 @@ export interface Config {
     readonly checkInterval: number;
     readonly stepDelay: number;
     readonly stepCount: number;
+    readonly stepSize: number;
+    readonly pattern: PatternName;
     readonly verbose: boolean;
 }
 
@@ -63,7 +71,9 @@ interface SeedShape {
     moveInterval: number;   // seconds
     checkInterval: number;  // seconds
     stepDelay: number;      // milliseconds
-    stepCount: number;      // pixels
+    stepCount: number;      // count
+    stepSize: number;       // pixels
+    pattern: string;        // strategy name
     verbose: boolean;
 }
 
@@ -72,12 +82,15 @@ function assertSeedShape(raw: unknown): asserts raw is SeedShape {
         throw new Error("scripts/config.default.json: root must be an object");
     }
     const r = raw as Record<string, unknown>;
-    for (const key of ["moveInterval", "checkInterval", "stepDelay", "stepCount"] as const) {
+    for (const key of ["moveInterval", "checkInterval", "stepDelay", "stepCount", "stepSize"] as const) {
         const v = r[key];
         if (typeof v !== "number" || !Number.isFinite(v) || v <= 0) {
             throw new Error(`scripts/config.default.json: '${key}' must be a positive finite number (got ${JSON.stringify(v)})`);
         }
     }
+    if (typeof r.pattern !== "string" || !isPatternName(r.pattern)) {
+        throw new Error(`scripts/config.default.json: 'pattern' must be a known strategy name (got ${JSON.stringify(r.pattern)})`);
+    }
     if (typeof r.verbose !== "boolean") {
         throw new Error(`scripts/config.default.json: 'verbose' must be a boolean (got ${JSON.stringify(r.verbose)})`);
     }
@@ -98,6 +111,8 @@ export const DEFAULT_CONFIG: Config = {
     checkInterval: seed.checkInterval * 1000,
     stepDelay:     seed.stepDelay,
     stepCount:     seed.stepCount,
+    stepSize:      seed.stepSize,
+    pattern:       seed.pattern,
     verbose:       seed.verbose,
 };
 
@@ -110,10 +125,12 @@ export const DEFAULT_CONFIG: Config = {
  * Numeric fields are in CLI / config-file units:
  *   moveInterval, checkInterval — seconds
  *   stepDelay                   — milliseconds
- *   stepCount                   — pixels
+ *   stepCount                   — count
+ *   stepSize                    — pixels
  *
- * `verbose` is `boolean | undefined` like the numeric fields, so all five
- * fields share the same "first defined value wins" precedence logic.
+ * `pattern` is a strategy name (`string | undefined`) and `verbose` is
+ * `boolean | undefined`, so every field shares the same "first defined
+ * value wins" precedence logic.
  *
  * For the CLI specifically, `verbose` is `undefined` when `-V/--verbose`
  * was not passed and `true` when it was. There is no CLI off-switch
@@ -126,6 +143,8 @@ export interface ConfigOverrides {
     readonly checkInterval: number | undefined;
     readonly stepDelay: number | undefined;
     readonly stepCount: number | undefined;
+    readonly stepSize: number | undefined;
+    readonly pattern: string | undefined;
     readonly verbose: boolean | undefined;
 }
 
@@ -192,6 +211,8 @@ export function resolveConfig(file: ConfigOverrides | null, cli: ConfigOverrides
         checkInterval: pickSeconds(cli.checkInterval, file?.checkInterval, DEFAULT_CONFIG.checkInterval),
         stepDelay:     pickRaw(cli.stepDelay,         file?.stepDelay,     DEFAULT_CONFIG.stepDelay),
         stepCount:     pickRaw(cli.stepCount,         file?.stepCount,     DEFAULT_CONFIG.stepCount),
+        stepSize:      pickRaw(cli.stepSize,          file?.stepSize,      DEFAULT_CONFIG.stepSize),
+        pattern:       pickRaw(cli.pattern,           file?.pattern,       DEFAULT_CONFIG.pattern),
         verbose:       pickRaw(cli.verbose,           file?.verbose,       DEFAULT_CONFIG.verbose),
     };
 }