chore(governance): migrate the 4 un-issued loops onto the ladder (declare current tiers, no behavior change)

[williamzujkowski]

Part of #3839. Depends on #3841.

Context

Per the vote: migration unbundled; THIS issue covers only the loops with no existing dedicated issue — suggest_research_tasks (suggest), improvement_review (suggest), pr_review (advisory), tune loop (enforce-bounded). The other five live cases keep their own issues (#3552, #3769, #3815, #2077, #3697 — absorbed into the epic). Strictly documentation+declaration: each loop's manifest/config declares its CURRENT tier; zero behavior changes (Scope Steward condition).

Acceptance criteria

• 4 tier declarations landed, each verifiable against the recon evidence (file:line in the epic table)
• CI gate from feat(orchestration): machine-enforce the manifest authority tier (router + CI gate) #3841 green (no undeclared loops remain)
• tune loop's enforce declaration documents its bounds (floor/cap/decay) as the tier's safety envelope

Evidence required

Gate green; per-loop assertion tests.

Out of scope

ANY tier promotion/demotion (separate ratified events).