feat(directives): add 15 engagement-specific directives + tags.toml entries

conductor/directives/directive_one_concept_per_file/meta.md

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+# directive_one_concept_per_file
+
+## v1
+
+**Why this iteration:** New rule, no prior source. Encodes the existing practice (every directive is one concept) as an explicit rule for future harvesters.
+**Source:** new rule
+
+---
+**Lifted:** 2026-07-05

conductor/directives/directive_one_concept_per_file/v1.md

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+# One directive per directory — do not combine two rules in one `v1.md`
+
+## What it says
+
+Each directive directory (`conductor/directives/<name>/`) contains exactly ONE rule in its `v1.md`. Do not combine two related-but-distinct rules into a single `v1.md`. If a rule has two parts that could be independently tagged, split into two directives.
+
+## Why
+
+Directives are independently tagged (the 6-dim `tags.toml`), independently composed into presets, and independently tested. A `v1.md` that combines "ban `dict[str, Any]`" and "ban `Optional[T]` returns" cannot be tagged with a single subject (data-structures vs error-handling) and cannot be independently included in a preset (one without the other). One concept per file keeps the directive atomic.
+
+## See also
+
+- `conductor/directives/verbatim_lift_not_rewrite` — the harvest rule
+- `conductor/directives/warm_md_duplicates_not_in_place` — the `.warm.md` duplicate rule