feat(skills): add golang-refactoring skill (#76)

* feat(skills): add golang-refactoring skill

Adds a new skill covering the safe, at-scale process of refactoring
existing Go code: a coverage-adaptive safety net, tool-driven
behavior-preserving transforms (gopls Rename/Inline/Extract, gofmt -r,
eg, gopatch, go/analysis fixers), the Fowler refactoring catalog mapped
to Go, breaking import cycles and moving types across packages via
type-alias gradual code repair, and a human-in-the-loop workflow of
small staged PRs landed on a refactoring branch.

The workflow persists its plan in the code itself via `// REFACTOR(step
N): ...` markers (seeded when the refactoring branch is created, for
large refactors only) since a multi-step refactor outlasts any single
session's context, delegates each staged change to a sub-agent so the
orchestrating session only keeps short results, and keeps intermediate
PRs out of draft while the final merge-to-main PR is opened as one.

The skill owns the process; it cross-references golang-naming,
golang-project-layout, golang-code-style, golang-design-patterns,
golang-modernize, golang-security/golang-safety, golang-lint,
golang-testing, golang-benchmark, and golang-gopls for target-state
rules and mechanics owned elsewhere, and those first five skills
gained a reciprocal cross-reference back. golang-how-to's skill
loading table, categories, and competing-clusters disambiguation are
updated accordingly.

* docs(golang-refactoring): reformat skill body into concise bullet lists

Convert dense prose paragraphs across SKILL.md and all references/*.md
into nested bullet points for scannability, without changing any rule,
rationale, table, code block, or cross-reference.

* chore(skills): bump version of skills cross-referencing golang-refactoring

code-style, design-patterns, how-to, modernize, naming, and project-layout
each gained a cross-reference to the new golang-refactoring skill; bump
their patch version per the repo version-discipline convention.

* fix(golang-refactoring): correct grammar in persona line (land change -> land changes)

README.md

@@ -151,7 +151,7 @@ These skills are designed as **atomic, cross-referencing units**. A skill may re
 │ structs-iface│ │ data-structs │ │ observability   │ │ stay-updated     │
 │ documentation│ │ database     │ │                 │ │ dep-management   │
 │ lint         │ │ modernize    │ │                 │ │ gopls            │
-│ security     │ │              │ │                 │ │                  │
+│ security     │ │ refactoring  │ │                 │ │                  │
 └──────────────┘ └──────────────┘ └─────────────────┘ └──────────────────┘
 
     ┌─────────────────────────────────────────────────────────────────────────┐
@@ -197,6 +197,7 @@ These skills are designed as **atomic, cross-referencing units**. A skill may re
 | ⭐️ | ✅ `golang-how-to` | ⚡ | — | 165 | 2,254 | 10,372 |
 | ⭐️ | ✅ `golang-modernize` | ⚡ 🤖 | -61% | 68 | 2,780 | 9,093 |
 | ⭐️ | ✅ `golang-naming` | ⚡ ⚙️ | -23% | 158 | 2,865 | 7,233 |
+| ⭐️ | ✅ `golang-refactoring` | ⚡ 🧠 🤖 ⚙️ | — | 246 | 3,639 | 19,840 |
 | ⭐️ | ✅ `golang-safety` | ⚡ | -58% | 78 | 2,457 | 5,227 |
 | ⭐️ | ✅ `golang-testing` | ⚡ 🧠 🤖 ⚙️ | -32% | 113 | 3,105 | 6,212 |
 | ⭐️ | ✅ `golang-troubleshooting` | ⚡ 🧠 🤖 | -32% | 126 | 2,735 | 15,901 |
@@ -314,6 +315,10 @@ Idiomatic Go design patterns. Functional options, constructors, builder pattern,
 
 Modernize Go code to use recent language features. Range-over-int, min/max builtins, iterators, slices/maps/cmp/slog stdlib packages, testing patterns (t.Context, b.Loop, synctest), and tooling upgrades.
 
+#### `golang-refactoring`
+
+Safe, at-scale refactoring process for existing Go code. Coverage-adaptive safety net, tool-driven behavior-preserving transforms (gopls Rename/Inline/Extract, gofmt -r, eg, gopatch), the Fowler catalog mapped to Go, breaking import cycles, type-alias gradual code repair, and a human-in-the-loop workflow of staged PRs on a refactoring branch.
+
 ### QA & Performance
 
 #### `golang-benchmark`