fix(server): keep users' keys at their own endpoints, and more fixes from the third review

- Bedrock: a user's AWS keys no longer go to an endpoint the server sets
  in AWS_ENDPOINT_URL_BEDROCK_RUNTIME / AWS_ENDPOINT_URL (read by the
  upgraded SDK), and admin panel keys win over AWS_BEARER_TOKEN_BEDROCK,
  as the Test button checks them. Checked with Bedrock.
- Ollama: a server key without a base URL (admin panel, OLLAMA_API_KEY)
  goes to Ollama Cloud, as env.example says, instead of 127.0.0.1.
- Quota: EdgeOne counts whatever key header comes along, keyless Ollama at
  a private address counts, and their provider texts stay in the log.
- An EdgeOne server model (admin panel, ai-models.json) works: the route
  checked the raw provider header, which holds the name's slug.
- parse-url ends downloads it does not read (too large, PDF, errors).
- Desktop app: the port follows where the chats are (IndexedDB per
  origin) instead of a remembered port, which could hide them for good;
  a same-port restart tells the page to refetch the server models; a
  failed preset switch no longer undoes a newer choice; a presets file
  removed after a failed read can be saved again; .env values quoted from
  start to end keep their inner quotes, as dotenv reads them.

tests/unit/env-loader.test.ts

@@ -0,0 +1,42 @@
+// @vitest-environment node
+import { mkdtempSync, writeFileSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import { afterEach, describe, expect, it, vi } from "vitest"
+
+const dir = vi.hoisted(() => ({ path: "" }))
+vi.mock("electron", () => ({
+    app: {
+        getPath: (name: string) =>
+            name === "exe" ? `${dir.path}/app/exe` : dir.path,
+        getAppPath: () => `${dir.path}/app`,
+    },
+}))
+
+import { loadEnvFile } from "@/electron/main/env-loader"
+
+const KEYS = ["T_JSON", "T_COMMENT", "T_PLAIN", "T_DOUBLE"]
+afterEach(() => {
+    for (const k of KEYS) delete process.env[k]
+})
+
+describe("loadEnvFile", () => {
+    it("reads quoted values like dotenv", () => {
+        dir.path = mkdtempSync(join(tmpdir(), "env-loader-"))
+        writeFileSync(
+            join(dir.path, ".env"),
+            [
+                // An apostrophe inside a single-quoted JSON value
+                `T_JSON='{"name":"Team's models"}'`,
+                `T_COMMENT="value" # a comment`,
+                "T_PLAIN=plain  # a comment",
+                `T_DOUBLE="say "hi""`,
+            ].join("\n"),
+        )
+        loadEnvFile()
+        expect(process.env.T_JSON).toBe(`{"name":"Team's models"}`)
+        expect(process.env.T_COMMENT).toBe("value")
+        expect(process.env.T_PLAIN).toBe("plain")
+        expect(process.env.T_DOUBLE).toBe(`say "hi"`)
+    })
+})