fix(patterns) redraw ten more ASCII diagrams under 78 columns

[mjmirza]

Batch 13 of the ASCII-diagram width remediation pass.

Ten entries redrawn so every diagram line stays under 78 columns,
across families 03, 04, 05, 06, 07, 08, 15, and 21.

• key-rotation
• emergency-lever
• encapsulate-collection
• do-not-repeat-yourself
• service-oriented-architecture
• concrete-table-inheritance
• identity-field
• dynamic-router
• message-channel
• cqrs

Multi-branch layouts (a fan-out registry, a before/after code pair,
a two-column consumer fan, a parallel read/write split) are redrawn
as vertical chains with the branch relationship named in prose,
the same simplification used in batches 7 through 12.

Gates run clean. check-structure.py (884/884), check-family-names.py,
check-prose.py (925/925), markdownlint-cli2 0.23.2 (0 issues),
validate-refs.py --strict (every citation resolves), check-code.py
--strict (2826 compiled, 0 failed). gen-indexes.py regenerated all
affected family README.md tables.

[mjmirza]

REVIEWED. Approve. This is batch 13 of the ASCII-diagram width-remediation
pass. Ten diagram sections redrawn under the 78-column limit,
spanning eight families (03, 04, 05, 06, 07, 08, 15, 21).

Real diff confirmed via gh pr diff --name-only. 17 files, 10
content entries plus 7 family README.md index regenerations
(03-refactoring's README byte count was already correct after
the redraw, so it carries no diff, matching the local check).

CI. every real check (markdown style, structure and prose, code
samples compile, citations resolve, PR security check) reports
pass across both check-suite runs on this PR. The two
skipping entries are the claim check and PR security check on
the pre-merge-fix commit, superseded by the green re-run on the
post-merge-fix commit.

Merge history. this PR conflicted with batch 12 (PR #435) on
two family READMEs, 06-enterprise-application-architecture and
07-integration, since both batches touched overlapping families
in parallel branches. Resolved via the standard recipe. git
fetch, merge origin/main, take main's version on the conflicted
READMEs, regenerate all family indexes fresh via gen-indexes.py,
commit the regeneration separately, push. PR flipped from
CONFLICTING to CLEAN/MERGEABLE and CI re-ran green on the
merge-fix commit.

Gate sequence (check-structure.py 884/884, check-family-names.py,
check-prose.py 925/925, markdownlint-cli2 0.23.2 0 issues,
validate-refs.py --strict all citations resolve, check-code.py
--strict 2826 compiled 0 failed) all ran clean locally before
push, and gen-indexes.py was re-run after the merge-fix so both
conflicted family README byte counts reflect batch 12 and batch
13 correctly.

One entry, emergency-lever, carries a Category 18 word
(lever) as a legitimate literal filename component, not
figurative usage. check-prose.py's own gate ran clean on this
entry, confirming the false-positive is a write-tool-level
guard limitation, not a real prose violation.

Single review pass, low blast radius. pure diagram-fence
replacements in already-published entries, no prose or
reference changes outside the diagram sections and the
generated index tables.