refactor(docs)!: rename CLI binary to corestack-docs

go install names binaries after the directory, so cmd/docs installed an
ambiguous `docs` binary into $GOBIN that could clobber or be clobbered
by other tools. Move it to cmd/corestack-docs, matching corestack-goose,
and update goreleaser, CI, docs and usage text. Accepted ADRs keep their
text and gain a dated rename note.

BREAKING CHANGE: `go install go.auvem.com/corestack/cmd/docs@latest`
stops resolving after the next tag; use cmd/corestack-docs. @v0.1.0
still installs the old `docs` binary.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/docs-format.md

@@ -1,6 +1,6 @@
 # Docs format
 
-This is the complete specification for architecture decision records (ADRs) and implementation plans checked by `docs check`. It is standalone: a file that follows this document is valid without running the tool. The words MUST, MUST NOT and MAY are used in their RFC 2119 sense.
+This is the complete specification for architecture decision records (ADRs) and implementation plans checked by `corestack-docs check`. It is standalone: a file that follows this document is valid without running the tool. The words MUST, MUST NOT and MAY are used in their RFC 2119 sense.
 
 The ADR body uses the [MADR 4](https://adr.github.io/madr/) layout; `Consequences` is mandatory. The frontmatter, naming and cross-reference rules are specific to this format.
 
@@ -135,7 +135,7 @@ Heading text is the raw source after the `#` markers, trimmed, with any closing
 
 ### 6.3 Placeholders
 
-A record is invalid if it still contains the exact marker `{{docs:todo}}` anywhere outside code, including inside a frontmatter string value or list item (write it quoted there: `summary: "{{docs:todo}}"`). A list item equal to the marker reports only the marker error, not the format error for its key. `docs new` writes this marker into each field and section it leaves for you to fill; replace it with content. No other text is treated as a placeholder, so words like TODO or TBD are fine. To mention the marker itself, put it in inline or fenced code.
+A record is invalid if it still contains the exact marker `{{docs:todo}}` anywhere outside code, including inside a frontmatter string value or list item (write it quoted there: `summary: "{{docs:todo}}"`). A list item equal to the marker reports only the marker error, not the format error for its key. `corestack-docs new` writes this marker into each field and section it leaves for you to fill; replace it with content. No other text is treated as a placeholder, so words like TODO or TBD are fine. To mention the marker itself, put it in inline or fenced code.
 
 ## 7. References and links
 
@@ -156,9 +156,9 @@ URL:
 
 Always allowed in body prose only: in-page anchors (`#section`) and `mailto:` links. Any other scheme is rejected.
 
-## 8. What `docs check` reports
+## 8. What `corestack-docs check` reports
 
-`docs check [--root DIR]` checks every record under `DIR` (default: the working directory) and prints one line per problem:
+`corestack-docs check [--root DIR]` checks every record under `DIR` (default: the working directory) and prints one line per problem:
 
 ```
 path:line: message