[codex] Add environment-aware artifact fetching

[n30nex]

Summary

• add --env tdeck|tdeck-meshcore to scripts/fetch_tdeck_artifact.py
• select env-specific artifact names and default output directories
• clear stale generated bundle files before re-downloading into an existing artifact directory
• validate FLASH_MANIFEST.txt against the requested artifact environment, treating missing env as standard tdeck
• teach scripts/release_evidence.py to generate matching standard or MeshCore evidence commands and detect stale manifest/env mismatches
• update release/flash/troubleshooting/upgrade docs for the opt-in MeshCore TDM artifact path

Validation

• git diff --check
• python -m py_compile scripts\\fetch_tdeck_artifact.py scripts\\release_evidence.py scripts\\tdeck_smoke.py scripts\\tdm_airtime_smoke.py
• python scripts\\tdm_airtime_smoke.py --selftest
• python scripts\\fetch_tdeck_artifact.py --env tdeck --repo ItsLimitlezz/LimitlezzOS --run-id 27872850182 --commit 378bde99cf23ebd35e123d0d2759b945f91dca92 --out .pio\\ci-artifacts\\fetch-env-standard-test
• python scripts\\fetch_tdeck_artifact.py --env tdeck-meshcore --repo ItsLimitlezz/LimitlezzOS --run-id 27872850182 --commit 378bde99cf23ebd35e123d0d2759b945f91dca92 --out .pio\\ci-artifacts\\fetch-env-meshcore-test
• negative guard: requesting --env tdeck-meshcore with the standard artifact name fails with Downloaded artifact environment mismatch: manifest has tdeck, expected tdeck-meshcore.
• python scripts\\release_evidence.py --env tdeck-meshcore --repo ItsLimitlezz/LimitlezzOS --branch codex/display-safe-chat-text --commit 378bde99cf23ebd35e123d0d2759b945f91dca92 --artifact-dir .pio\\ci-artifacts\\fetch-env-meshcore-test --port COM8
• GitHub Actions Firmware CI run 27873369637 passed for head 6810b85e2c4f1d1407ddaacf7bbf747410d9d6f3
• exact PR artifact fetched with python scripts\\fetch_tdeck_artifact.py --env tdeck-meshcore --repo ItsLimitlezz/LimitlezzOS --run-id 27873369637 --commit 6810b85e2c4f1d1407ddaacf7bbf747410d9d6f3
• manifest: env=tdeck-meshcore, meshcore_enabled=1, budget_status=pass, firmware_bytes=1578368, static_ram_bytes=230196

Hardware

• COM8 enumerated as USB Serial Device (COM8), VID/PID 303A:1001, status OK
• flashed the exact tdeck-meshcore artifact from run 27873369637 to COM8 with direct no-stub esptool; ESP32-S3 rev v0.2, MAC cc:8d:a2:0d:14:28, all write hashes verified
• python scripts\\tdeck_smoke.py --port COM8 --env tdeck-meshcore --skip-upload --open-timeout 60 --boot-timeout 90 --timeout 45 --no-expect --commands id sys net rf stats wifi "companion test" -> PASS
• smoke evidence: identity !a20d1428 "limitlessdeck" (LIMI), battery 100% USB, RAM 42/151KB, Meshtastic on, MeshCore on, companion test PASS
• python scripts\\tdm_airtime_smoke.py --port COM8 --open-timeout 60 --boot-timeout 60 --timeout 30 -> PASS
• TDM evidence: verified MT/MC split modes 60/40, balanced 50/50, and 40/60; switch count advanced from 342 to 350 with zero late timing; restored to Meshtastic on, MeshCore off