refactor: move buildable .NET source into src/, update CI/doc paths

Groups the repo root into src (buildable source), docs (already existed),
and everything else (db/, scripts/, tests/, deploy/ - deployment/ops/test
assets that aren't compiled, already organized as their own folders). CI
now only needs src/ to build: dotnet restore/build/test/publish all point
at src/TaxBaik.sln, src/TaxBaik.Web/, src/TaxBaik.Proxy/.

- git mv every project (Domain, Infrastructure, Application,
  Application.Tests, Web, Web.Client, Proxy) and TaxBaik.sln into src/ as a
  unit, so relative ProjectReference/.sln paths stay valid unchanged.
- .gitea/workflows/deploy.yml: 6 dotnet restore/clean/build/test/publish
  invocations now point at src/. db/migrations and scripts/ stay at root
  (deploy_gb.sh and browser-e2e.yml only touch published output and the
  deployed URL, not source paths - verified, no changes needed there).
- scripts/validate_admin_render.sh: admin render-mode file paths now
  src/TaxBaik.Web.Client/...
- scripts/validate_kst_timestamps.sh: dropped deploy.sh from its target
  list - that script was removed in the prior cleanup commit (dead, no
  CI workflow referenced it) but this validator still expected it to exist.
- CLAUDE.md, docs/ENGINEERING_HARNESS.md, docs/ADMIN_PATTERN_CRITIQUE_WBS.md:
  updated project-structure diagram, dotnet run/build commands, and grep
  targets to the new src/ paths (also fixed a pre-existing stale path in
  ADMIN_PATTERN_CRITIQUE_WBS.md that still said TaxBaik.Web/Components/Admin
  from before that ever moved to TaxBaik.Web.Client).
- Added a Repo Root harness rule + Architecture Guardrail entries: new files
  belong under src/docs/tests/scripts/db/deploy, not loose at root; temp
  work stays outside the repo (or under a gitignored .scratch/) and is
  never committed.

Verified locally: dotnet build/test src/TaxBaik.sln (26/26 tests), and all
three scripts/validate_*.sh pass against the new layout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/TaxBaik.Web/Controllers/TaxFilingController.cs

@@ -0,0 +1,84 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using TaxBaik.Application.Services;
+using TaxBaik.Domain.Entities;
+
+namespace TaxBaik.Web.Controllers;
+
+[ApiController]
+[Route("api/[controller]")]
+[Authorize]
+public class TaxFilingController : ControllerBase
+{
+    private readonly TaxFilingService _taxFilingService;
+
+    public TaxFilingController(TaxFilingService taxFilingService)
+    {
+        _taxFilingService = taxFilingService;
+    }
+
+    [HttpGet("upcoming")]
+    public async Task<IActionResult> GetUpcoming([FromQuery] int daysAhead = 30)
+    {
+        var filings = await _taxFilingService.GetUpcomingAsync(daysAhead);
+        return Ok(new { data = filings });
+    }
+
+    [HttpGet("client/{clientId}")]
+    public async Task<IActionResult> GetByClientId(int clientId)
+    {
+        var filings = await _taxFilingService.GetByClientIdAsync(clientId);
+        return Ok(new { data = filings });
+    }
+
+    [HttpGet("{id}")]
+    public async Task<IActionResult> GetById(int id)
+    {
+        var filing = await _taxFilingService.GetByIdAsync(id);
+        if (filing == null)
+            return NotFound(new ProblemDetails { Title = "신고 일정을 찾을 수 없습니다.", Status = StatusCodes.Status404NotFound });
+
+        return Ok(filing);
+    }
+
+    [HttpPost]
+    public async Task<IActionResult> Create([FromBody] TaxFiling filing)
+    {
+        try
+        {
+            var filingId = await _taxFilingService.CreateAsync(filing);
+            var result = await _taxFilingService.GetByIdAsync(filingId);
+            return CreatedAtAction(nameof(GetById), new { id = filingId }, result);
+        }
+        catch (Exception ex)
+        {
+            return BadRequest(new ProblemDetails { Title = ex.Message, Status = StatusCodes.Status400BadRequest });
+        }
+    }
+
+    [HttpPut("{id}")]
+    public async Task<IActionResult> Update(int id, [FromBody] TaxFiling filing)
+    {
+        filing.Id = id;
+        try
+        {
+            await _taxFilingService.UpdateAsync(filing);
+            var result = await _taxFilingService.GetByIdAsync(id);
+            if (result == null)
+                return NotFound(new ProblemDetails { Title = "신고 일정을 찾을 수 없습니다.", Status = StatusCodes.Status404NotFound });
+
+            return Ok(result);
+        }
+        catch (Exception ex)
+        {
+            return BadRequest(new ProblemDetails { Title = ex.Message, Status = StatusCodes.Status400BadRequest });
+        }
+    }
+
+    [HttpDelete("{id}")]
+    public async Task<IActionResult> Delete(int id)
+    {
+        await _taxFilingService.DeleteAsync(id);
+        return NoContent();
+    }
+}