starmap: surface strategy reasoning and support/lowering signal

[fkguo]

What

An external portfolio of argument graphs (nine compiled packages reviewed side by side) surfaced a set of clarity gaps in the gaia inspect starmap surfaces. This PR fixes them across graph.json, the dot/SVG emitter, and the interactive HTML, plus a CLI-docs drift found along the way.

Graph exports and renderers (feat(starmap))

• Strategy reasoning was silently dropped. The graph.json exporter read a top-level reason key that compiled IR never carries (Strategy has no such field, extra="forbid"), so every strategy node shipped an empty reason. The exporter now joins steps[].reasoning and falls back to metadata.reason — the two places the DSL's reason= actually compiles to. In the reviewed portfolio this restored 12/12 previously-empty explanations per graph.
• Support vs lowering is now visually encoded. Strategy nodes and their conclusion edges carry a signed effect = cp[-1] - cp[-2] from the inline conditional-probability table (the premise present/absent contrast at every given count — the two gated slots _infer_conditional_probabilities writes). Both renderers color scored conclusion edges on the same red-grey-green ramp and scale stroke width by magnitude; the side panel shows the probability pair and an effect badge. Strategy forms without an inline CPT stay unscored and keep plain role styling.
• Generated helper nodes no longer dominate the layout. Knowledge nodes with metadata.generated start collapsed (with their incident edges) behind a default-off filter bucket, instead of being the dominant visual structure; search skips hidden nodes and sheds stale highlights.
• Legends tell the truth per graph. The HTML legend hides rows for absent kinds and gains two edge-color rows; the stellaris SVG legend scopes glyph rows to the strategy/operator types actually present and documents the edge colors whenever the graph carries scored edges (the standalone SVG has no hover panel, so its legend is the only decoding surface).
• Exported root claims get a topbar banner with the current root belief, click-to-open-panel.

The shipped starmap_assets/template.html is rebuilt from viz/.

CLI docs drift (docs(cli))

The galileo and mendel CLI-authored walkthroughs and docs/reference/cli/author.md still showed --label as the Python-binding flag; the author verbs migrated to --dsl-binding-name (note/question/variable have no --label at all; claim's optional --label requires the binding flag; relation verbs treat --label as the engine label kwarg). Every invocation now matches what tests/cli/galileo_demo/test_equivalence.py actually runs on each PR gate; gaia bayes's own --label binding convention is documented as intentionally different.

Testing

• make check green: 2936 passed (full suite), ruff + mypy --strict + hygiene hooks, 116 baseline snapshots unchanged-or-passing.
• 14 new unit tests: reason extraction (steps / metadata / precedence), effect math incl. the multi-given gated-CPT lock, effect edge styling replaces (not appends) role styling, legend type-scoping and effect rows, _has_effect_edges gating.
• End-to-end verified against a real nine-package portfolio: all previously-empty strategy reasons restored, edges colored by sign, zero-operator graphs no longer show operator legend rows, tsc --noEmit clean, template placeholder intact.
• graph.json changes are purely additive keys; the in-repo consumers (_wiki/_obsidian/_inquiry/github export) read IR or the parameterization payload and are unaffected (their suites pass).