Retire active TLC 4.5 repository integration

[MichaelSaucier]

Retires the active TLC 4.5 integration while preserving historical governance evidence.

Changes:

• remove the TLC 4.5 reusable-workflow caller
• remove the exact TLC 4.5 CODEOWNERS block
• preserve unrelated ownership rules and all TLC 4.6/TLC 5 controls

[MichaelSaucier]

Independent cross-family adversarial review: PASS for exact head 06423110f6a332b789503e85f961004402b4e033; blocker count 0. Reviewer route: Anthropic Claude Code / Claude Opus 5 (max), independent from the OpenAI Codex author family. Complete two-file diff inspected; unrelated ownership and TLC 4.6/TLC 5 controls preserved; ordinary CI green. Session 53957d0a-87b9-419a-9a35-f15685346fbb, result 04fd984c-1e11-4cfe-bf0f-622ee12279e6. This evidence is exact-head only and does not itself authorize merge.