Rewrite REPO_POLICIES.md sentence by sentence (closes #136)

Every sentence of prompts/REPO_POLICIES.md is rewritten against the
sentence rules: one idea per sentence, about 30 words at most, lists as
bulleted lists, subject and verb early, the main rule before any
exception. No rule's meaning changed: nothing is added, removed,
loosened or tightened, every reason stays, and code blocks, digests,
URLs, file names, commands and quoted strings are unchanged. Both repo
checklists carry the same rewrite of the sentences they quote word for
word.

Model: fable-5-1

TODO.md

@@ -21,6 +21,13 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-11-04: Rewrote `prompts/REPO_POLICIES.md` sentence by sentence
+  (https://git.eeqj.de/sneak/prompts/issues/136), on sneak's yes at
+  https://git.eeqj.de/sneak/prompts/issues/136#issuecomment-165193. Every rule
+  keeps its meaning and its place, and `must` and `should` stay as they were.
+  Long sentences are split, comma-chained lists are now bulleted lists, and
+  every reason stays. Code blocks, digests, URLs, file names, commands and
+  quoted strings are unchanged.
 - 2026-11-03: The canonical golangci-lint is now v2.15.0, still built with
   go1.27.0, so the `go` directive rule is unchanged (issue 142). Repositories
   pick this up on their next re-vendor. Each item in the canonical