docs(agents): AGENTS.md + CLAUDE.md rules only — narratives, dates and quotations out; issue ownership written by role (#15856)

* docs(agents): AGENTS.md + CLAUDE.md rules only — narratives, dates and quotations out; ownership written by role

- every rule kept as one executable sentence in its section; incident retellings, provenance stories and
  date-stamped measurements leave (AGENTS.md 1161 -> 1058 lines, CLAUDE.md 36 -> 41)
- the claim paragraph rewritten by role: the assignee is a presence bit set by the owning session, the
  Claim: comment is the identity, a dispatched executor inherits the assignee, verifies the newest Claim:
  names its branch, posts its own, never writes the field and never yields; release is an explicit act
- folded one rule each: the model-free agent commit trailer pair; the provenance sentence in the rules-only
  form (and the id-lint header sentence beside it); an ADR lives where the code it governs lives, cloud
  records cited as cloud ADR-NNNN; the PR-body footer as measured (session-URL survives a PATCH, the
  platform appends); a reading is a count plus the repository and commit it was taken against
- ratchet re-pinned down-only: AGENTS.md 1162 -> 1058 (widest table row 1081 -> 768), CLAUDE.md 86 -> 41

Co-authored-by: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019RfFHiRCSs3JXLK4cwcfox

* docs(agents): a dispatched executor posts no second Claim: — the dispatch's claim is its identity

- the ownership paragraph's executor clause (AGENTS.md and the CLAUDE.md excerpt): the owning session performs
  both acts; a PM dispatch sets the assignee (step 1) and posts the Claim: naming the dev's branch (step 2), both
  on the dev's behalf; the executor inherits both records, verifies the newest Claim: names its branch, posts no
  second claim (its own record is the report comment), never writes the assignee, never yields
- line-neutral in both files (1058 / 41); every other rule unchanged

Co-authored-by: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019RfFHiRCSs3JXLK4cwcfox

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Co-authored-by: Claude <noreply@anthropic.com>

Author: claude[bot]