refactor: P0-P3 fixes, C1 cleanup, architecture diagrams, go.work upgrade

- P0-1: ProviderError type + ReportStatus for precise 401/403 detection
- P0-2: Remove -config flag from deploy/homeagent.service
- P2-1: 5s debounce on context.go Save()
- P2-2→C1: Delete output_set_channel entirely
- P2-3: Extract mediaDataURL/mediaChat helpers
- P2-4: Dedup defaultSources var
- P3: Delete dead packages (embed/tokenizer/container/snapshot)
- P3: Delete dead functions (messagesToMap, RunStageAll)
- CL: Update .gitignore, docs, Makefile, gojieba removal
- Config: Delete config/config.yaml, update docs
- Arch: Remove EmitOutputTo from emitResponse
- CL-1: go.work 1.19→1.21
- Docs: Add Mermaid architecture diagrams to README
- Docs: Add kernel-rebuild requires plugin-rebuild note to PLUGIN_DEV.md

third_party/homeagent-sdk/sdk/settings.go

@@ -1,58 +0,0 @@
-package sdk
-
-type SettingsAPI interface {
-	// Get reads the plugin's own config value (config_<name> table).
-	Get(key string) (interface{}, error)
-
-	// Set writes a config value to the plugin's own config table.
-	Set(key string, value interface{}) error
-
-	// List returns all keys matching the given prefix.
-	List(prefix string) ([]string, error)
-
-	// GetCore reads the core config table.
-	GetCore(key string) (interface{}, error)
-
-	// SetCore writes to the core config table.
-	SetCore(key string, value interface{}) error
-
-	// ListCore lists core config keys matching the prefix.
-	ListCore(prefix string) ([]string, error)
-
-	// GetPlugin reads another plugin's config table.
-	GetPlugin(plugin, key string) (interface{}, error)
-
-	// SetPlugin writes to another plugin's config table.
-	SetPlugin(plugin, key string, value interface{}) error
-
-	// ListPlugin lists another plugin's config keys matching the prefix.
-	ListPlugin(plugin, prefix string) ([]string, error)
-
-	// RegisterDef registers a config definition for UI display.
-	RegisterDef(def ConfigDef)
-
-	// Defs returns config definitions matching the prefix.
-	Defs(prefix string) []*ConfigDef
-
-	// Dump returns all config values.
-	Dump() map[string]interface{}
-
-	// Plugins returns a list of all plugin config namespaces.
-	Plugins() []string
-}
-
-// ConfigDef describes a configuration field for the WebUI.
-type ConfigDef struct {
-	Key         string      `json:"key"`
-	Default     interface{} `json:"default,omitempty"`
-	Type        string      `json:"type"`
-	DisplayName string      `json:"display_name"`
-	Description string      `json:"description,omitempty"`
-	Category    string      `json:"category,omitempty"`
-	Options     []string    `json:"options,omitempty"`
-	Min         float64     `json:"min,omitempty"`
-	Max         float64     `json:"max,omitempty"`
-	Step        float64     `json:"step,omitempty"`
-	Required    bool        `json:"required,omitempty"`
-	Secret      bool        `json:"secret,omitempty"`
-}