feat(logging): add configurability for log levels preference

[kunalk16]

📝 Description

As of now, in the latest release, when we perform commands such as "picoclaw agent", it defaults to log level info and if we use the --debug parameter with the "picoclaw agent" command, it overrides to log level debug. Users may or may not be needing the logging and hence, this PR is adding configurability to the logging.

🗣️ Type of Change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 📖 Documentation update
• ⚡ Code refactoring (no functional changes, no api changes)

🤖 AI Code Generation

• 🤖 Fully AI-generated (100% AI, 0% Human)
• 🛠️ Mostly AI-generated (AI draft, Human verified/modified)
• 👨‍💻 Mostly Human-written (Human lead, AI assisted or none)

🔗 Related Issue

Closes #1848

📚 Technical Context (Skip for Docs)

• Reference URL:
• Reasoning:

🧪 Test Environment

• Hardware: Dell Laptop(test was executed in a container)
• OS: Ubuntu 25.10(container)
• Model/Provider: Azure OpenaAI GPT 5.3 Chat
• Channels: N/A

📸 Evidence (Optional)

Click to view Logs/Screenshots

**Before the change** **log level INFO by default**

After the change
Default config after onboarding

Config updated to log level fatal

Config updated to log level error

Config updated to log level debug

Config updated to log level with invalid value falls back to info

Config overridden to log level debug when --debug parameter is used

☑️ Checklist

• My code/docs follow the style of this project.
• I have performed a self-review of my own changes.
• I have updated the documentation accordingly.

[liuy]

#1828 is a lighter approach，no need add complexity I would suggest it

[kunalk16]

#1828 is a lighter approach，no need add complexity I would suggest it

Disagree, my approach is like any other enterprise grade application where we are having control over log levels through the config file. Not sure why it is being considered "complex"

[yinwm]

LGTM. Reviewed: default log level choice is intentional, tests are comprehensive, debug flag correctly overrides config.

[yinwm]

Related PR: #1828

This PR has a dependency relationship with #1828 (feat(logger): add PICOCLAW_LOG_FILE env var for file-only logging).

Why This PR Should Be Merged First

This PR (#1853) should be merged before #1828.

Reasons:

1. Initialization Order: This PR changes the initialization sequence - it moves LoadConfig() before the debug flag check, and calls SetLevelFromString() inside LoadConfig(). This establishes the correct order: config → log level → debug override.

2. No Breaking Changes: This PR is self-contained and doesn't depend on feat(logger): add PICOCLAW_LOG_FILE env var for file-only logging #1828's changes.

3. Rebase Simplicity: feat(logger): add PICOCLAW_LOG_FILE env var for file-only logging #1828 only adds one line (logger.ConfigureFromEnv()) to agent/helpers.go. Rebasing feat(logger): add PICOCLAW_LOG_FILE env var for file-only logging #1828 onto this PR is straightforward.

4. Logical Priority: Log level configuration (this PR) is more fundamental than log destination configuration (feat(logger): add PICOCLAW_LOG_FILE env var for file-only logging #1828). Setting the level first makes semantic sense.

Conflict Files

File	This PR	#1828
cmd/picoclaw/internal/agent/helpers.go	Moves debug/LoadConfig order	Adds ConfigureFromEnv() call
pkg/logger/logger.go	Adds ParseLevel, SetLevelFromString	Adds DisableConsole, ConfigureFromEnv
pkg/logger/logger_test.go	Adds tests	Adds tests

After Merge: Action for #1828

Once this PR is merged, #1828 should:

1. Rebase onto updated main

2. Place logger.ConfigureFromEnv() after LoadConfig() call

3. Ensure the final order is:
   ```go
   // 1. Load config (sets log level)
   cfg, err := internal.LoadConfig()

   // 2. Apply env var overrides (feat(logger): add PICOCLAW_LOG_FILE env var for file-only logging #1828)
   logger.ConfigureFromEnv()

   // 3. Debug flag has highest priority
   if debug {
   logger.SetLevel(logger.DEBUG)
   }
   ```

Feature Relationship

This PR (#1853)	#1828
Controls log level (what)	Controls log destination (where)
log_level: "debug" in config	PICOCLAW_LOG_FILE=/tmp/agent.log
Config file + env var	Env var only

Both features work together:
```bash

Set log level via config, log destination via env

PICOCLAW_LOG_FILE=/var/log/picoclaw.log picoclaw agent

(config.json has "log_level": "debug")

```

---

Recommendation: ✅ This PR is ready to merge. Please approve and merge before #1828.

[huaaudio]

Hi @kunalk16 , thanks for the pr! I noticed the log change from the current main branch. However, for the config, it is a bit improper here to put log_level inside "agents", as it is not the log of the agent. Maybe consider changing it under "gateway" or somewhere could make more sense? Also, it would be really good to document the change. Thanks in advance for your help!