docs: rename CLAUDE.md to AGENTS.md and rebrand provider-agnostic

Delete CLAUDE.md in favor of AGENTS.md as the orientation doc, rebrand
the project from Codex-bottle to provider-agnostic bot-bottle, and
repoint every CLAUDE.md reference across PRDs, research notes, the
implementer agent example, and the yaml_subset comment.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/research/pipelock-assessment.md

@@ -486,7 +486,7 @@ plausibly run pipelock on the host and skip Docker entirely.
 ### Where bot-bottle does work pipelock does not
 
 The redundancy argument breaks down once the actual goals from
-`CLAUDE.md` are enumerated:
+`AGENTS.md` are enumerated:
 
 1. **Filesystem isolation that survives a misbehaving agent.** Docker
    containers give an entire kernel-mediated mount namespace and a separate
@@ -584,7 +584,7 @@ some other way. That is not the use case the project was built for.
 
 2. **Does the pipelock Docker image introduce supply-chain risk?**
    Pulling `ghcr.io/luckypipewrench/pipelock:latest` brings in a binary
-   from an unvetted source. Pinning by digest (as the CLAUDE.md recommends
+   from an unvetted source. Pinning by digest (as the AGENTS.md recommends
    for supply-chain hygiene) and building from source are both options.
 
 3. **What is the actual DLP false-positive rate for the secrets bot-bottle