Remove dev session support branching

[isaacroldan]

Summary:

• Remove the supportsDevSessions client capability and make dev-session behavior unconditional.
• Delete the legacy Partner Dashboard preview/scopes branches from app dev.
• Default generated app configs to automatically update URLs on dev.
• Remove unused developer preview helpers left behind by the cleanup.

Validation:

• pnpm knip
• pnpm vitest run packages/app/src/cli/services/dev.test.ts packages/app/src/cli/services/dev-clean.test.ts packages/app/src/cli/services/dev/ui.test.tsx packages/app/src/cli/services/dev/urls.test.ts packages/app/src/cli/services/dev/processes/setup-dev-processes.test.ts packages/app/src/cli/services/app/config/link.test.ts packages/app/src/cli/services/app/config/link-service.test.ts
• pnpm --filter app type-check
• pnpm --filter app lint

[isaacroldan]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Remove unused extension creation surface #8023
• Remove atomic deployment support flag #8022
• Remove store search support flag #8021
• Remove legacy developer preview concepts #8020
• Remove dev session support branching #8019 👈 (View in Graphite)
• Remove deprecated draftable extension process #8018
• Remove deprecated 1P dev mode #8017
• main

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[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/private/node/constants.d.ts

@@ -6,7 +6,6 @@ export declare const environmentVariables: {
     doctor: string;
     enableCliRedirect: string;
     env: string;
-    firstPartyDev: string;
     noAnalytics: string;
     optOutInstrumentation: string;
     appAutomationToken: string;

packages/cli-kit/dist/public/node/context/local.d.ts

@@ -63,13 +63,6 @@ export declare function alwaysLogAnalytics(env?: NodeJS.ProcessEnv): boolean;
  * @returns True if SHOPIFY_CLI_ALWAYS_LOG_METRICS is truthy.
  */
 export declare function alwaysLogMetrics(env?: NodeJS.ProcessEnv): boolean;
-/**
- * Returns true if the CLI User is 1P.
- *
- * @param env - The environment variables from the environment of the current process.
- * @returns True if SHOPIFY_CLI_1P is truthy.
- */
-export declare function firstPartyDev(env?: NodeJS.ProcessEnv): boolean;
 /**
  * Returns true if the CLI can run the "doctor-release" command.
  *