docs(#2802): standardize tier terminology with descriptive prefixes

[fullsend-ai-coder]

Replace bare "Tier N" references across documentation, ADRs, problem docs, and agent prompts/skills with descriptive-prefix forms to eliminate ambiguity between the three distinct tier systems in this codebase:

• "credential delivery tier" for the ADR 0025 four-tier credential
  model (tiers 1-4: prefetch, providers, REST server, host files)
• "intent authorization tier" for the intent-representation.md
  four-tier change authorization model (tiers 0-3: standing rules,
  tactical, strategic, organizational)
• "configuration tier" for the three-tier config inheritance model
  (upstream defaults, org config, per-repo overrides)

Add a terminology convention entry to AGENTS.md documenting the three tier systems and the requirement to always use a descriptive prefix.

Files updated across 28 docs, ADRs, problem docs, skills, and agent prompts. External tier references (e.g. "GitLab Free tier") are left unchanged. Plan docs with already-contextual "fallback tier" references are also unchanged.

Note: pre-commit and make lint could not run due to sandbox network restrictions preventing shellcheck installation. The post-script runs an authoritative pre-commit check on the runner.

---

Closes #2802

Post-script verification

• Branch is not main/master (agent/2802-standardize-tier-terminology)
• Secret scan passed (gitleaks — 1d4efff9e2d2cdbe2f13e3af03c0dc98a9468f98..HEAD)
• Pre-commit hooks passed (authoritative run on runner)
• Tests ran inside sandbox

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[codecov]

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[fullsend-ai-retro]

🤖 Finished Retro · ✅ Success · Started 10:00 AM UTC · Completed 10:27 AM UTC
Commit: 2bc52d6 · View workflow run →

[fullsend-ai-retro]

Retro: PR #2885 — Standardize tier terminology

Workflow timeline:

1. /fs-triage on issue Standardize 'tier' terminology to always use descriptive prefix #2802 → triage agent labeled ready-to-code (3 min)
2. Code agent created PR docs(#2802): standardize tier terminology with descriptive prefixes #2885 across 28 docs files (+156/−144) in ~19 min
3. Review agent was not dispatched — the is_event_actor_authorized check rejected the bot actor (already tracked in dispatch: ADR 0054 authorization gate blocks review dispatch for coder-bot PRs #2674)
4. Human (rh-hemartin) approved ~6 min after PR opened, with no inline comments
5. PR merged ~2 hours later

Code quality assessment: The code agent correctly identified the three distinct tier systems and accurately classified every reference. However, it applied prefixes mechanically everywhere — producing compound adjectives like "higher-intent-authorization-tier authorization" and repeating "credential delivery tier" 10 times in 5-sentence paragraphs where context was already clear. One semantic error occurred: "compatibility tier" in agent-compatible-code.md was changed to "compatibility classification" even though it was not one of the three defined tier types. Heading renames created new anchor slugs without evidence that all inbound cross-references were verified.

Skipped proposals (already tracked):

• Review agent not dispatched for bot PRs → dispatch: ADR 0054 authorization gate blocks review dispatch for coder-bot PRs #2674
• Mechanical code changes without contextual awareness → partially covered by Code agent: avoid uniform changes across semantically distinct code paths #935
• Skip retro for PRs with no review findings → Unify retro skip conditions: skip when review verdict is clean approval with no findings #2749, Skip retro dispatch for merged bot PRs with no agent interaction #2739

Filed proposals: 2 — both target fullsend-ai/fullsend.

Proposals filed

• Code agent should verify all inbound cross-references when renaming markdown headings (in fullsend-ai/fullsend)
• Code agent should apply first-mention-then-abbreviate pattern for repetitive terminology conventions (in fullsend-ai/fullsend)