refactor: drop dev-cycle-profile.yml for conventions + CLAUDE.md facts

The profile was never parsed — it was prose the skill bodies told the model to read, so most slots were dead, constant across every project, or fiction (the whole pipeline block, including the "tdd is opt-in" claim, was enforced by nothing).

Split it in two: constants become fixed conventions named directly by the skills (new docs/conventions.md), and the few genuinely per-project facts move to each project's CLAUDE.md under '## Skills plugin: project facts'. tdd/fieldtest/docwriter are now always available; the only behavioural toggle left is spec auto-sign.

Delete docs/profile-schema.md and templates/project-profile.yml; add docs/conventions.md and a project-facts section to templates/CLAUDE.md.fragment; rewrite all SKILL/agent prose and the pipeline/design/migration/README/INSTALL docs accordingly.

issue/SKILL.md

@@ -88,8 +88,8 @@ artefact mirrored to Gitea ("would it be committed → English", per
 `tea` is pre-authenticated via its own config (`~/.config/tea/`).
 Never read or echo that file — it holds a token. `tea` auto-detects
 the repository from the git remote; override with `--repo owner/name`
-when running outside the repo (the slug lives in
-`issue_tracker.repo` if a project profile sets it).
+when running outside the repo (the project's issue tracker — its
+CLAUDE.md project facts name the repo slug and the list/show commands).
 
 | Operation | Command |
 |---|---|