docs: migrate ts_client detailed design from docs/features/time_slave

[ryan-steel]

Description

Migrates ts_client DD from old docs/features time_slave documentation to match the S-CORE folder layout. This treats ts_client as its own component since it has its own source subdir and is used by both time_daemon and time_slave.

Related ticket

Part of #97

⚠️ Diff Warning

This PR is part of a stack but shows diff from main instead of add-ts_client-component-requirements due to cross-fork limitations.

The diff below includes all commits from the base of the stack, not just this layer.

After lower PRs merge, update the base branch to see only this layer's changes.

Stack Info

Part of stacked PR chain (layer 3 of 3):

1. docs: add module_template docs boilerplate to ts_client #177
2. Add ts client component requirements #149
3. docs: migrate ts_client detailed design from docs/features/time_slave #178 (this PR)

Commits in this layer: 2

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run //:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.6.0) and connecting to it...
INFO: Invocation ID: 558d0dd6-7505-4867-bcad-de25e5fd2c89
Computing main repo mapping: 
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Loading: 
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Analyzing: target //:license-check (4 packages loaded)
Analyzing: target //:license-check (4 packages loaded, 0 targets configured)
Analyzing: target //:license-check (4 packages loaded, 0 targets configured)

Analyzing: target //:license-check (45 packages loaded, 10 targets configured)

Analyzing: target //:license-check (89 packages loaded, 10 targets configured)

Analyzing: target //:license-check (146 packages loaded, 3116 targets configured)

Analyzing: target //:license-check (159 packages loaded, 6206 targets configured)

Analyzing: target //:license-check (159 packages loaded, 6206 targets configured)

Analyzing: target //:license-check (164 packages loaded, 6255 targets configured)

Analyzing: target //:license-check (164 packages loaded, 6255 targets configured)

Analyzing: target //:license-check (167 packages loaded, 8142 targets configured)

Analyzing: target //:license-check (170 packages loaded, 11342 targets configured)

Analyzing: target //:license-check (171 packages loaded, 11350 targets configured)

Analyzing: target //:license-check (171 packages loaded, 11350 targets configured)

Analyzing: target //:license-check (171 packages loaded, 11350 targets configured)

INFO: Analyzed target //:license-check (172 packages loaded, 11476 targets configured).
[11 / 16] checking cached actions
INFO: From Generating Dash formatted dependency file ...:
INFO: Successfully converted 2 packages from Cargo.lock to bazel-out/k8-fastbuild/bin/formatted.txt
[13 / 16] JavaToolchainCompileClasses external/rules_java+/toolchains/platformclasspath_classes; 0s disk-cache, processwrapper-sandbox
[15 / 16] Building license.check.license_check.jar (); 0s disk-cache, multiplex-worker
INFO: Found 1 target...
Target //:license.check.license_check up-to-date:
  bazel-bin/license.check.license_check
  bazel-bin/license.check.license_check.jar
INFO: Elapsed time: 33.132s, Critical Path: 2.44s
INFO: 16 processes: 12 internal, 3 processwrapper-sandbox, 1 worker.
INFO: Build completed successfully, 16 total actions
INFO: Running command line: bazel-bin/license.check.license_check ./formatted.txt <args omitted>
usage: org.eclipse.dash.licenses.cli.Main [-batch <int>] [-cd <url>]
       [-confidence <int>] [-ef <url>] [-excludeSources <sources>] [-help] [-lic
       <url>] [-project <shortname>] [-repo <url>] [-review] [-summary <file>]
       [-timeout <seconds>] [-token <token>]

[github-actions]

The created documentation from the pull request is available at: docu-html