Carry the fork's style-override sentence into the product instructions (fork-prompt retirement)

[aarontrowbridge]

Problem — The fork's prompt patches (redundant with this repo's AGENTS.md
injection, retiring with the fork) carry one load-bearing sentence: the product
style overrides any earlier terseness/monospace instruction. Stock harness
prompts default to terse one-word answers and can fight the injected style
without it.

Fix — Carry that single override sentence into the product's AGENTS.md
instruction file so the injected style wins under any harness.

AC — The override sentence is present in the instruction file's Style
section; a config-content test (if one exists) still passes.

Prior art — The fork's prompt patch (read via the remote branch
origin/local/amicode); the product AGENTS.md instruction file.