feat(tools): implement CRUD operations for thoughts and projects

* Add tools for creating, retrieving, updating, and deleting thoughts.
* Implement project management tools for creating and listing projects.
* Introduce linking functionality between thoughts.
* Add search and recall capabilities for thoughts based on semantic queries.
* Implement statistics and summarization tools for thought analysis.
* Create database migrations for thoughts, projects, and links.
* Add helper functions for UUID parsing and project resolution.

internal/config/loader.go

@@ -0,0 +1,113 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+func Load(explicitPath string) (*Config, string, error) {
+	path := ResolvePath(explicitPath)
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, path, fmt.Errorf("read config %q: %w", path, err)
+	}
+
+	cfg := defaultConfig()
+	if err := yaml.Unmarshal(data, &cfg); err != nil {
+		return nil, path, fmt.Errorf("decode config %q: %w", path, err)
+	}
+
+	applyEnvOverrides(&cfg)
+	if err := cfg.Validate(); err != nil {
+		return nil, path, err
+	}
+
+	return &cfg, path, nil
+}
+
+func ResolvePath(explicitPath string) string {
+	if strings.TrimSpace(explicitPath) != "" {
+		return explicitPath
+	}
+
+	if envPath := strings.TrimSpace(os.Getenv("OB1_CONFIG")); envPath != "" {
+		return envPath
+	}
+
+	return DefaultConfigPath
+}
+
+func defaultConfig() Config {
+	return Config{
+		Server: ServerConfig{
+			Host:         "0.0.0.0",
+			Port:         8080,
+			ReadTimeout:  15 * time.Second,
+			WriteTimeout: 30 * time.Second,
+			IdleTimeout:  60 * time.Second,
+		},
+		MCP: MCPConfig{
+			Path:       "/mcp",
+			ServerName: "amcs",
+			Version:    "0.1.0",
+			Transport:  "streamable_http",
+		},
+		Auth: AuthConfig{
+			Mode:       "api_keys",
+			HeaderName: "x-brain-key",
+			QueryParam: "key",
+		},
+		AI: AIConfig{
+			Provider: "litellm",
+			Embeddings: AIEmbeddingConfig{
+				Model:      "openai/text-embedding-3-small",
+				Dimensions: 1536,
+			},
+			Metadata: AIMetadataConfig{
+				Model:       "gpt-4o-mini",
+				Temperature: 0.1,
+			},
+		},
+		Capture: CaptureConfig{
+			Source: DefaultSource,
+			MetadataDefaults: CaptureMetadataDefault{
+				Type:          "observation",
+				TopicFallback: "uncategorized",
+			},
+		},
+		Search: SearchConfig{
+			DefaultLimit:     10,
+			DefaultThreshold: 0.5,
+			MaxLimit:         50,
+		},
+		Logging: LoggingConfig{
+			Level:  "info",
+			Format: "json",
+		},
+	}
+}
+
+func applyEnvOverrides(cfg *Config) {
+	overrideString(&cfg.Database.URL, "OB1_DATABASE_URL")
+	overrideString(&cfg.AI.LiteLLM.BaseURL, "OB1_LITELLM_BASE_URL")
+	overrideString(&cfg.AI.LiteLLM.APIKey, "OB1_LITELLM_API_KEY")
+	overrideString(&cfg.AI.OpenRouter.APIKey, "OB1_OPENROUTER_API_KEY")
+
+	if value, ok := os.LookupEnv("OB1_SERVER_PORT"); ok {
+		if port, err := strconv.Atoi(strings.TrimSpace(value)); err == nil {
+			cfg.Server.Port = port
+		}
+	}
+}
+
+func overrideString(target *string, envKey string) {
+	if value, ok := os.LookupEnv(envKey); ok {
+		*target = strings.TrimSpace(value)
+	}
+}