feat: add native-only FME environment get, create, update, and delete

[ravindraharness]

Description

Follow-up to #806 for remaining FME environment ops.

#806 dual-moded list only (workspace_id or org_id+project_id). MCP never had get/create/update/delete on workspace_id, so those four ops are Harness-native only. This PR does not invent a legacy Split v2 MCP contract (those Admin APIs exist; we are not exposing them).

Dual-mode routing — this PR only

Resource	Legacy (workspace_id)	Harness-native (org_id+project_id)
fme_environment	list (unchanged dual-mode)	list + get / create / update / delete

Native contracts

• list — still dual-mode. Native list uses fmeV4PaginatedListExtract (data → items, totalCount → total) with offset/limit (harness_list size maps to limit).
• get — GET /fme/api/v4/environments/{environment_id} (UUID from list, not the env name).
• create — POST /fme/api/v4/environments body { name, isProduction? } (CreateEnvironmentRequest). Name max 15 characters. production is accepted as an alias for isProduction. skipScopeBodyInjection so NG orgIdentifier/projectIdentifier are not injected.
• update — PATCH JSON Merge Patch { name?, isProduction? }. Neither field is clearable (omit to keep).
• delete — DELETE /fme/api/v4/environments/{id}. Backend returns 400 hasDependents while SDK API keys (always created by EnvironmentStarterKit), flags, or segments remain. MCP has no v4 token resource and does not auto-delete keys.

workspace_id on get/create/update/delete throws: Harness-native (org_id/project_id) only — MCP never supported workspace_id for this operation (list remains dual-mode).

Key implementation changes

• src/registry/toolsets/feature-flags.ts plus tests/README.
• src/registry/extractors.ts — fmeV4PaginatedListExtract used by native environment list (same helper as traffic type / rollout status lists).
• resolveNativeOnlyEnvironmentRoute for the four new ops. List still uses resolveFmeDualMode.
• README Feature Flags matrix: fme_environment get/create/update/delete. Native list envelope/pagination documented without citing other PR numbers.
• No registry/index.ts, types.ts, or prompt changes.

Type of Change

• New feature

Checklist

• Unit: tests/registry/fme-environment-native-only.test.ts + tests/registry/feature-flags.test.ts
• pnpm docs:check (README matrix matches registry)

Coding Standards (registry-driven MCP model)

• No new server.registerTool() calls — existing feature-flags toolset extended
• operationPolicy on every new/changed endpoint
• Shared response extractors from src/registry/extractors.ts
• identifierFields and scope declared
• No console.log() in src/

Test plan

• Native create/get/update against qa.harness.io
• workspace_id rejected on get/create/update/delete
• Native delete: expected 400 hasDependents until starter-kit SDK keys are removed (no MCP token API)

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