refactor: remove dynamic toolsets and deprecated closure constructor

[SamMorrowDrums]

What & why

Removes the dynamic toolset discovery feature (the --dynamic-toolsets / GITHUB_DYNAMIC_TOOLSETS switch and the meta-tools enable_toolset, list_available_toolsets, get_toolset_tools) along with the deprecated closure-based NewServerToolWithDeps constructor that only existed to support it.

This is tech debt cleanup:

• Dynamic mode was local-only — never offered by the remote server.
• It carried real complexity: a separate config flag plumbed through stdio + http configs, a parallel registration path, four inventory methods (ToolsForToolset, IsToolsetEnabled, EnableToolset, EnabledToolsetIDs), an extra branch in ResolvedEnabledToolsets, three meta-tools, and a chunk of conformance/CI matrix.
• After this PR there are exactly two server-tool constructors:
  • NewServerTool — raw mcp.ToolHandler, no closure, no unmarshalling
  • NewServerToolWithContextHandler[In, Out] — typed handler, deps via context
• This repo isn't published as a stable library; downstream consumers can pin a version if they need the dynamic feature.

Diff highlights

• pkg/github/dynamic_tools.go + test → deleted
• pkg/inventory/server_tool.go — NewServerToolWithDeps removed
• pkg/inventory/filters.go — ToolsForToolset, IsToolsetEnabled, EnableToolset, EnabledToolsetIDs removed
• ResolvedEnabledToolsets(dynamic, toolsets, tools) → ResolvedEnabledToolsets(toolsets, tools)
• DynamicToolsets field removed from MCPServerConfig, StdioServerConfig, http ServerConfig
• --dynamic-toolsets flag removed
• ToolsetMetadataDynamic removed; AvailableToolsets("context", "dynamic") → AvailableToolsets("context")
• README, server-configuration.md, toolsets-and-icons.md, copilot-instructions.md, conformance-test script — dynamic refs stripped
• The .github/workflows/mcp-diff.yml change that drops the dynamic test matrix isn't included in this PR (OAuth scope) — please apply it as a follow-up

Verification

• ✅ script/lint clean
• ✅ script/test passes
• ✅ script/generate-docs produces no extra diff after this commit

Stacks on (now merged) #2511.

[Copilot]

Pull request overview

Removes the local-only dynamic toolset discovery feature and its supporting plumbing (meta-tools, config/flags, inventory APIs), and deletes the deprecated closure-based NewServerToolWithDeps constructor to simplify the tool registration surface area.

Changes:

• Removed dynamic toolset discovery mode end-to-end (CLI/env/config wiring, server registration path, docs, and conformance script coverage).
• Simplified inventory/tool registration by removing dynamic toolset management APIs and the deprecated closure-based tool constructor.
• Updated docs/help generation to exclude only the context toolset (since dynamic no longer exists).

Show a summary per file

File	Description
script/conformance-test	Removed dynamic-mode test paths and configs from conformance runner.
README.md	Removed dynamic tool discovery documentation and updated tool configuration guidance.
pkg/inventory/server_tool.go	Removed deprecated NewServerToolWithDeps constructor.
pkg/inventory/server_tool_test.go	Dropped tests for the removed constructor; kept/updated context-handler tests.
pkg/inventory/registry.go	Updated inventory doc comment to remove dynamic enabling reference.
pkg/inventory/registry_test.go	Removed tests for deleted dynamic toolset inventory APIs.
pkg/inventory/filters.go	Removed dynamic toolset management methods (ToolsForToolset, EnableToolset, etc.).
pkg/inventory/builder.go	Updated toolset config docs now that “dynamic empty toolsets” mode is gone.
pkg/http/server.go	Removed DynamicToolsets from HTTP server config.
pkg/http/handler.go	Removed dynamic-toolsets branching and updated toolset resolution call signature.
pkg/http/handler_test.go	Updated tests for new ResolvedEnabledToolsets signature.
pkg/github/tools.go	Removed ToolsetMetadataDynamic; updated toolsets help generation exclusion list.
pkg/github/server.go	Removed DynamicToolsets config and dynamic meta-tool registration; simplified toolset resolution.
pkg/github/server_test.go	Updated ResolvedEnabledToolsets tests to match new behavior/signature.
pkg/github/dynamic_tools.go	Deleted dynamic toolset management tools implementation.
pkg/github/dynamic_tools_test.go	Deleted tests for removed dynamic toolset management tools.
internal/ghmcp/server.go	Removed dynamic-toolsets config wiring and logging in stdio server setup.
docs/toolsets-and-icons.md	Removed the “Dynamic” toolset icon entry.
docs/server-configuration.md	Removed dynamic mode documentation and references.
docs/installation-guides/README.md	Removed mention of dynamic tool discovery.
cmd/github-mcp-server/main.go	Removed --dynamic-toolsets flag and associated viper binding/config propagation.
cmd/github-mcp-server/generate_docs.go	Updated toolset documentation generation to stop excluding dynamic.
.github/copilot-instructions.md	Removed dynamic toolsets env var/flag references from contributor guidance.

Copilot's findings

• Files reviewed: 24/24 changed files
• Comments generated: 1