chore(release): Bump version to 0.15.0

[arcaputo3]

Version bump for 0.15.0 "Fidelity" (wave 18 — field-hardening sweep, #409): all pins swept 0.14.0 → 0.15.0 (build.mill fallback, WorkbookMetadata.appVersion, plugin.json, README/QUICK-START/scripting dep lines, examples, xl-scripting SKILL.md + RECIPES.md), CHANGELOG heading, STATUS 0.15.0 block, API.md Series.fill snippet.

Gates: compile 810/810, full suite 1028/1028 (one #414 wall-clock flake on the parallel run, green in isolation + full rerun), examples ✓, skill snippets ✓ (--local), scalafmt CI form ✓, SNAPSHOT grep empty.

🤖 Generated with Claude Code

[claude]

Review: chore(release) — Bump version to 0.15.0

Mechanical release bump. I checked every changed pin against the authoritative version-location list in .claude/commands/release-prep.md and confirmed correctness. Looks good to merge. ✅

Verified

• All dependency pins bumped 0.14.0 → 0.15.0 across the full checklist surface: build.mill fallback, WorkbookMetadata.appVersion, plugin.json version, examples/project.scala, examples/README.md, README.md (dep + ivyDeps + per-module comments), docs/QUICK-START.md (Mill/sbt/scala-cli), docs/reference/scripting.md (all 5 headers), xl-scripting SKILL.md + RECIPES.md (all headers), and the scripting.scala scaladoc header. Matches the release-prep pin list one-for-one — including the historically-drifting plugin.json.
• No stray unbumped pins. A repo-wide grep confirms every remaining 0.14.0 is a legitimate historical/feature-annotation reference (CHANGELOG history, docs/design/error-propagation.md status, roadmap.md history, and "since 0.14.0" doc annotations) — correctly left untouched.
• CHANGELOG heading ## [0.15.0] "Fidelity" - 2026-07-17 added below [Unreleased]; STATUS.md "Last Updated" bumped and a detailed "New in 0.15.0" block added (reader/writer: custom numFmt whose formatCode equals a built-in degrades to General on read→write round-trip #404/evaluator: XIRR/XNPV date ranges reject raw serial Numbers — post-round-trip recalc poisons returns blocks #405/evaluator: variadic-aggregate direct blank args coerce to 0 instead of being ignored (COUNT/AVERAGE parity) #395/evaluator: remaining coercion edges — int positions, blank-in-date position, Bool cells in date positions #396/evaluator: defined names rejected in strict range-typed argument positions (=VLOOKUP(x, named_table, 2)) #394/charts: explicit series spPr + series color option (LO renders default-styled series invisible) #407/reader/lint: flag CT_Workbook child-order violations and unresolvable r:id references (Excel-repair class) #397/cli: hyperlink batch op passes '#'-prefixed internal targets into location verbatim #406).
• API.md snippet — the new Series.fill / Color.Rgb(0xFF307FE2) line is accurate: verified Series.fill: Option[Color.Rgb] (Chart.scala:98) and Color.Rgb(argb: Int) (Color.scala:12) both exist. This block has no //> using header, so verify-skill-snippets.sh correctly skips it (it's a reference one-liner, consistent with the surrounding list) — the undefined firstSeries is harmless there.
• No SNAPSHOT refs; no source-logic changes beyond the appVersion default.

Minor observations (non-blocking)

1. docs/plan/roadmap.md:15 still reads **Current Version**: **0.14.0 "Candor"** (released 2026-07-16). The release-prep authoritative grep surfaces this line, but it's not in the explicit pin checklist. If "Current Version" is meant to track the latest released tag, leaving it is correct (0.15.0 isn't tagged yet); if it tracks the working version, it should move to 0.15.0. Worth a quick confirm of intent.
2. docs/STATUS.md:158 still cites **3,996 tests** (verified ... 2026-07-09) — stale relative to this release's date and the PR body's 1028/1028 figure. Not this PR's job (test-count refresh isn't on the bump checklist), but a good candidate to refresh at tag time.
3. The wrapped trailing comment in the new API.md line reads slightly awkwardly across the break — purely cosmetic.

Gates reported in the PR body (compile, full suite, examples, skill snippets --local, scalafmt, empty SNAPSHOT grep) align with the release-prep verification steps. No security or performance surface in a version-string bump.