fix(sea): F2 round-2 — root-cause lazy-load + lint clean (DA M1)

DA round 2 findings on F2 / F4 / F3b H1 had a common root cause
the team-lead correctly flagged: `SeaNativeLoader.ts` does
`const native = require('../../native/sea/index.js')` at module
load, so any import from this module triggers the `.node`
artifact load. When `yarn build:native` hasn't run, that throws
MODULE_NOT_FOUND BEFORE mocha can fire `before()` skip-gates,
crashing test discovery for every e2e suite that imports
anything from this module — including transitive imports via
`DBSQLClient` → `SeaBackend` → `SeaNativeLoader`.

Round 1 dance: every e2e test got a `createRequire` +
filesystem-check workaround. Round 2 fixes the actual defect:
the loader itself memoises the require behind `getSeaNative()`,
so importing the module is free for code paths that never reach
SEA. Filesystem-check guards in the e2e tests stay as defense-
in-depth (they produce a friendlier "run yarn build:native"
diagnostic than napi-rs's raw MODULE_NOT_FOUND).

Verified the fix by moving the .node artifact aside and running
the F2 e2e: previously CRASHED at file load with
MODULE_NOT_FOUND; now SKIPS cleanly via the suite's `before()`
gate with an actionable message. Restored binary, re-ran the
test: passes against pecotesting in 480ms.

Also addresses F2 M1 lint:
- `lib/sea/SeaNativeLoader.ts:131` — added `import/extensions`
  to the eslint-disable comment on the lazy-require, since the
  `.js` extension is required (napi shim is CommonJS, not TS)
- `tests/e2e/sea/complex-types-e2e.test.ts:148` — switched to
  destructuring `const { schema } = table` per prefer-
  destructuring rule

Co-authored-by: Isaac
Signed-off-by: Madhavendra Rathore <madhavendra.rathore@databricks.com>

Author: msrathore-db

tests/e2e/sea/complex-types-e2e.test.ts

@@ -145,7 +145,7 @@ describe('SEA complex types — native Arrow default', function suite() {
       expect(batchEnvelope).to.not.equal(null);
 
       const table = tableFromIPC(batchEnvelope!.ipcBytes);
-      const schema = table.schema;
+      const { schema } = table;
 
       // Each complex column should be a native Arrow nested type, not Utf8.
       const arrField = schema.fields.find((f) => f.name === 'c_arr');