feat(telemetry): support AGENTCORE_TELEMETRY_DISABLED env var

[Hweinstock]

Spec

Problem: CI runs emit telemetry, adding noise on the refactor branch.

Definition of Done:

• Support the mainline env var AGENTCORE_TELEMETRY_DISABLED; when set to "true" or "1", telemetry is not emitted. Precedence: env var >> config >> default.
• Audit must still work.
• Inject the env var into each CI workflow that executes tests or CLI code.

Changes

• src/globalConfig/config.tsx: applyOverrides now gives AGENTCORE_TELEMETRY_DISABLED top precedence over config/default for telemetry.enabled. Name matches mainline. telemetry.audit is untouched, so audit still works. Disable-only semantics (matches mainline).
• .github/workflows/build.yml, unit-test.yml: set env: AGENTCORE_TELEMETRY_DISABLED: "1" at the reusable-workflow level. These are the only workflows that execute the CLI (agentcore --help smoke test) or tests (bun test). Set inside the reusable workflows because a caller's env: does not propagate into reusable workflows.
• src/globalConfig/config.test.tsx: table-driven unit tests for the precedence and audit behavior.

Verification

Unit / static checks

bun test src/globalConfig/   # 10 pass, 0 fail
bun run lint:check           # OK
bun run format:check         # OK
bun run typecheck            # OK

End-to-end (local OTLP collector + isolated HOME)

Minimal collector logs each /v1/metrics export to a file; the CLI points at it via config telemetry.endpoint=http://localhost:4318, with enabled and audit both true.

Scenario 1 — no env var (baseline):

$ agentcore config telemetry.enabled
true
# collector.log:
2026-09-01T00:28:54Z received /v1/metrics export (1251 bytes)
# audit file written:
~/.agentcore/telemetry/5724d7b5-...jsonl   (cli.command_run entry)

Scenario 2 — AGENTCORE_TELEMETRY_DISABLED=1:

$ AGENTCORE_TELEMETRY_DISABLED=1 agentcore config telemetry.enabled
false                        # env override forces resolved enabled=false (over config's true)
# collector.log: unchanged — NO new export received
# audit file STILL written:
~/.agentcore/telemetry/0a29f880-...jsonl   (audit still works)

Result: env var suppresses network telemetry with top precedence over config; audit is unaffected.

Reproduce

bun install
bun run compile:linux-x64
# terminal A: tiny OTLP collector on :4318 logging POSTs to /v1/metrics
# terminal B, isolated HOME with config { telemetry: { enabled:true, audit:true, endpoint:"http://localhost:4318" } }:
./dist/bin/agentcore-linux-x64 config telemetry.enabled                       # -> collector gets export + audit file
AGENTCORE_TELEMETRY_DISABLED=1 ./dist/bin/agentcore-linux-x64 config telemetry.enabled  # -> no export; audit file still written

[Hweinstock]

remove these tests and replace them with some on the e2e config handler.

[Hweinstock]

use a test.each and fix the failing tests