Switch to bun, add unit + integration tests

Replaces ts-node / ts-node-dev with bun for both running and watching.
Bun runs the existing TypeScript directly with no transpile step, and
its built-in test runner is what the new tests use.

- npm scripts rewritten in terms of `bun run` / `bun --watch run`
- Removed unused `node`, `@types/node`, `ts-node`, `ts-node-dev` deps
- Added `@types/bun` for `bun:test` types
- Dropped `package-lock.json` in favor of `bun.lock`
- `engines` now asks for bun >= 1.0

Tests live alongside source under `src/*.test.ts`:

- `encode.test.ts` covers `headerFor` and `inferOutFile` helpers (those
  are now exported from `encode.ts` so they're testable in isolation).
- `roundtrip.test.ts` writes a fixture XML to a temp dir, encodes it,
  decodes the result, and asserts byte-identical recovery — for both
  `.ewprj` and `.ms14` headers, for a payload large enough to span more
  than one PKWare section, and for an empty payload.

`bun test` runs all 11 tests; README documents `bun install` /
`bun run ewd` / `bun run ewe` / `bun test`.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: cinderblock

README.md

@@ -13,14 +13,16 @@ big files into 900 000-decompressed-byte sections; `ewe` mirrors that.
 
 ## Install
 
+Requires [bun](https://bun.sh) (≥ 1.0).
+
 ```bash
-npm i
+bun install
 ```
 
 ## Decode
 
 ```bash
-npm run ewd -- --verbose ./samples/Temp.ewprj ./samples/Design1.ms14
+bun run ewd --verbose ./samples/Temp.ewprj ./samples/Design1.ms14
 ```
 
 For each input, writes `<filename>.xml` next to it.
@@ -34,9 +36,9 @@ Options:
 ## Encode
 
 ```bash
-npm run ewe -- --verbose ./samples/Temp.ewprj.xml
+bun run ewe --verbose ./samples/Temp.ewprj.xml
 # or with explicit output:
-npm run ewe -- --output ./out.ewprj ./samples/Temp.ewprj.xml
+bun run ewe --output ./out.ewprj ./samples/Temp.ewprj.xml
 ```
 
 By default, strips a trailing `.xml` from each input to derive the output
@@ -59,11 +61,21 @@ still valid: a decode/encode/decode round-trip on every sample tested
 produces byte-identical XML, and the resulting files are accepted by
 `ewd`. Improving compression density is a `node-pkware` problem.
 
+## Tests
+
+```bash
+bun test
+```
+
+Covers unit tests for the encoder's filename helpers and round-trip
+integration tests (tiny `.ewprj`, tiny `.ms14`, multi-block payload that
+spans more than one PKWare section, and an empty payload).
+
 ## Development
 
 ```bash
-npm run dev:ewd -- --verbose ./samples/Temp.ewprj
-npm run dev:ewe -- --verbose ./samples/Temp.ewprj.xml
+bun run dev:ewd --verbose ./samples/Temp.ewprj
+bun run dev:ewe --verbose ./samples/Temp.ewprj.xml
 ```
 
-Both use `ts-node-dev` for fast reload.
+Both use `bun --watch` for fast reload on source changes.