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.

debug/SKILL.md

@@ -28,8 +28,8 @@ dispatch, and handoff.
 
 Trigger this skill on:
 
-- a failing run of the project's test command (configured under
-  `commands.test` in the profile)
+- a failing run of the project's test command (its CLAUDE.md
+  project facts)
 - wrong stdout from running a project artefact
 - a segfault from a built binary
 - a panic / unhandled exception in the toolchain
@@ -43,8 +43,7 @@ for TDD" is the exact failure mode this skill exists to prevent.
 `debug` is for a regression of *existing* behaviour. New
 test-specifiable behaviour is its sibling `tdd`'s job (same
 two-stage RED→GREEN shape, triggered by a feature description
-rather than an observed misbehaviour) — route there instead,
-on profiles that enable it.
+rather than an observed misbehaviour) — route there instead.
 
 ## The Iron Law