v2.12.0 - Shrink the always-loaded agent instruction weight (ADR-0029)

ADR-0029 — shrink the always-loaded agent instruction weight (idea 0021, amends ADR-0014).

AGENTS.md is injected as custom instructions before every session and re-stated each normative rule ~twice (derived spec body + the non-derived ## Agent operating guidance block). This release states each rule once and rewrites the guidance block to principle + pointer form.

Changed

• Compacted the canonical spec starter/docs/working-method.md (15.3 KB → 13.7 KB).
• Rewrote both ## Agent operating guidance blocks (AGENTS.md, starter/AGENTS.md) to principle + pointer; removed the verbatim-duplicated Refresh procedure (now spec-only).
• Regenerated the derived AGENTS.md body (21.9 KB → 18.6 KB, ~1k tokens/session), which also reconciled two drifts: the Refresh procedure now sits in the lifecycle section, and overview-regeneration wording matches ADR-0016.
• Spec optimized agent-first; guide.md already narrates every trimmed concept, so nothing was lost (verified: no rule, status, or field name dropped).
• Provenance bumped to v2.12 across the three starter/ renderings.

Adopter migration

None. Prose-compaction only, no behavioral change; the tightened text reaches adopters automatically via the copy-driven "bring me current" update (ADR-0022).