Add admin API and tdbg command to dump dynamic config values

[chaptersix]

This implements issue #421: adds GetDynamicConfig RPC to the admin service and a corresponding 'tdbg config list' command to dump all registered dynamic config settings along with their configured override values.

Changes:

• Extended GenericSetting interface with Description() and DefaultValue() methods
• Added ListSettings() to registry for enumerating all registered settings
• Added GetConfiguredValues() to Collection for retrieving configured overrides
• Added proto definitions for GetDynamicConfig request/response
• Implemented GetDynamicConfig in admin handler
• Added tdbg config list command with key filtering support
• Added tests for Description(), DefaultValue(), ListSettings(), GetConfiguredValues()

What changed?

Describe what has changed in this PR.

Why?

Tell your future self why have you made these changes.

How did you test it?

• built
• run locally and tested manually
• covered by existing tests
• added new unit test(s)
• added new functional test(s)

Potential risks

Any change is risky. Identify all risks you are aware of. If none, remove this section.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ chaptersix
❌ claude
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[chaptersix]

> ./tdbg config list --filter history.enablechasmcallbacks -v
Found 1 dynamic config settings:

history.enablechasmcallbacks
  Precedence: Namespace
  Default: false
  Description: Controls whether new callbacks are created using the CHASM implementation
           instead of the previous HSM backed implementation.
  Values:
    {namespace:default}=true

> ./tdbg config list --filter history.enablechasmcallbacks
Found 1 settings (use -v for details)

 KEY                           PRECEDENCE  DEFAULT  VALUES
 history.enablechasmcallbacks  Namespace   false    {namespace:default}=true

>  ./tdbg config list --filter history.enablechasmcallbacks --json | jq
[
 {
   "key": "history.enablechasmcallbacks",
   "precedence": "Namespace",
   "default": "false",
   "values": [
     {
       "constraints": {
         "namespace": "default"
       },
       "value": "true"
     }
   ],
   "description": "Controls whether new callbacks are created using the CHASM implementation\ninstead of the previous HSM backed implementation."
 }
]

[chaptersix]

do we need a type swtich?

[chaptersix]

simplify?

[chaptersix]

will need to re-open. claude is preventing to license check from passing

[chaptersix]

Closing in favor of existing PR.